This unnamed alien race; sometimes referred to as Greys, Chigs, Aquoids, or Landsharks, are a caste-based species who launched a surprise invasion on Earth, most likely motivated by a need for a new home or colony. It is theorized that they invaded to take hold of Earth's resources, specifically liquid water. During the initial invasion they used an orbital insertion, mistaken for a cluster of meteors, to deploy their forces.
The aliens are divided into four known warrior castes, but there are likely more non-combatant castes. Analysis of the warrior castes' biology indicates that they are highly developed, sporting redundant arteries and other blood vessels. Their heads are entirely sensory organs; their brains are located in a cavity behind their hearts, directly attached to the spine. The aliens have large numbers of stem cells and platelets, enabling them to regenerate whole limbs that may be lost in combat. Their hardened exoskeleton allows them to take multiple 5.56 mm shots before being too injured to continue fighting, functioning similarly to a Kevlar vest. Instead of a mouth, these creatures possess a sort of bladder which uses vibrations to create sound.
All of the warrior-caste aliens have substantial amounts of machinery implanted into their bodies, including communication, cooling, and weapons systems. Their perception is also very acute, supplementing their precognitive and retrocognitive abilities.
Known warrior castes
The Infantry Caste can be identified by their lack of grasping hands, replaced by weapons grafted onto each arm. Their average height is about 8'1" (~ 2.4 meters). While they are taller than Humans, they are proportionately thinner. As of the initial invasion, they are estimated to be the most abundant caste, with around 25 million in total. Certain members of the Infantry Caste have been seen acting as leaders for others of the same caste.
Like the other castes, the heads of Infantry soldiers are nothing but sensory organs. All of their vital organs are concentrated behind layers of muscle and arteries in the right area of their chests. A cooling system is also integrated into their bodies, with a heat-dispersing fan located in front of their organs. Unlike many of the other castes, they do not have as much machinery located on their back.
The Officer Caste are identifiable by their tall, slender build and four mechanical legs. They have an average height of 9'4" (~ 2.8 meters). The Officers are specialized in commanding groups of infantry, augmented by an unusually large, well-developed brain and very keen eyesight which has been supplemented with additional electronics. They are the least numerous caste, numbering roughly 2,000,000. Officers have been seen leading groups of Operations Caste, which range in size from fire-teams of four to units of around a dozen.
The Officer caste have the most substantial amount of cybernetic enhancements. Their legs have been wholly replaced, enabling them to move at speeds of up to 40 kph / 24.8 mph with relative ease. Their legs are equipped with thrusters, similar to those on the drones, that allow them to hover rather than walk. Their right arm has an implanted weapons system that trades firepower for accuracy, while their left grasping hand has been replaced by a mechanical claw.
The Operations Caste shares many similarities with the Infantry Caste, with a few notable exceptions. The Operations average about 6'11" (~ 2.1 meters). The special forces appear to be a more intelligent Infantry soldier, able to undertake specialized goals beyond that of simple shock troops. They also appear to be a middling caste, lacking the firepower of the Infantry and the intelligence of the Officer. While their strength is unknown, it is likely that they are between 2,000,000 and 8,000,000 in number.
Unlike the officer and infantry castes, the Operations have retained their left grasping hand and are able to make use of hand signals. Their weapons systems sport greater accuracy than those of the general infantry, but a less-powerful grenade launcher.
The Intelligence Caste is likely specialized in their namesake, gathering information and laying down lines of communication. Averaging about 5'10" (~ 1.7 meters), the Intelligence Caste are the shortest and stockiest of all known warrior castes. It is unknown how many Intelligence Caste members there are.
Unlike all other warrior castes, the Intelligence Caste lacks any integrated weapons systems. However, they retain the large amount of cooling and communications machinery grafted to their backs. The lack of weaponry is made up for by their ability to utilize both grasping hands, which they use to operate machinery and vehicles, such as driving ground artillery platforms and operating walking guns.
Known non-combat castes
The known non-combat castes appear to be highly specialized and modified aliens. Their anatomy is radically different from that of the warrior castes.
The Water Extractor is a specialized, partially biological pump that is used to move massive amounts of water quickly, growing as large as 100 feet (~ 30 meters) in height. The Extractor's organs have been greatly reduced and compacted, leaving only organs that are vital to life functions. Extractors are highly intelligent and use an advanced form of communication to coordinate their actions for maximum efficiency.
The Extractors are deployed along with the initial invasion force, landing off-shore and using modified tentacles to quickly pull water from the surrounding environment. During the invasion, the Extractor Caste works in concert with Wedge Ships that provide power and elevation for pumping water.
It is known that there are "Medics" in the aliens' ground forces. It is not clear if the "Intel" caste actually performs this function due to the bio-mechanical nature of their biology, or if this is referring to a similar caste which is more focused on medical support. During the fight on the freeway bridge, standard Operations Caste aliens were seen dragging an incapacitated Operations Caste alien back to safety, establishing they don't simply abandon their wounded.
Culture and society
The homeworld of the aliens is described as a chaotic, possibly war-torn place. The aliens involved in the invasion of Earth are not the dominant force in their homeland, but a losing power who are "invading out of desperation under high-stakes circumstances".
Based on their apparent desire for the Earth's water supplies, it is likely that the aliens' homeworld is a watery planet.
The military doctrine of this species seems to be concentrated on the principles of rapid dominance: using superior maneuverability and firepower to achieve a coordinated and devastating first-strike. This seems to come at the cost of armor protection, relatively speaking, for both infantry and vehicles. The alien vehicles tend to be very maneuverable, but to have exposed positions for their operators. Their battle doctrine seems to be based on the concept of eliminating enemy resistance before it can mount a coordinated retaliation.
Indeed, it seems that the concept of heavily armored units meant to survive protracted combat is an alien concept to this race, as their forces seem relatively unprepared to fight Human armored vehicles, and lose their combat edge when fighting Human infantry in long battles of attrition. Their infantry weapons fire incendiary rounds, which are devastating against unprotected Human infantry. However, surprisingly for the weapons of a technologically advanced alien race, Human infantry body armor and flak jackets are able to provide reasonable protection against these incendiary rounds.
It seems that the aliens have embraced coordinated combined-arms tactics to the point that each element of their military is only proficient at one specialized role: their infantry are proficient at fighting other infantry, and their vehicles are proficient at fighting other vehicles. Battle doctrine seems to be that when alien infantry encounters enemy vehicles, they are supposed to call in combined-arms support; sometimes from their light field artillery or hover-jeeps, but more often from unmanned-drone airstrikes. Conversely, their vehicle-based weapons - both field artillery and aerial drones - seem much more focused against other vehicles. While, certainly, an airstrike will damage Human infantry, it is a disproportionate level of force which would have been better tasked against vehicles. The "walking-gun" field artillery, for example, fires a missile-volley which seems better suited for assaulting vehicles, as opposed to say, an up-scaled-version of their anti-personnel incendiary-round hand-held weapons. The result of this unit specialization is that they do not seem adept at asymmetric warfare tactics.
Alien infantry are repeatedly observed being outmatched by Human military vehicles. An M1 Abrams tank was able to adequately pin down a squad of alien infantry on the freeway, until they had to call in light artillery support. Alien infantry are also seen having a difficult time handling a small USMC squad driving LAV-25 APCs, which easily mowed past them. Alien infantry are never seen using infantry-wielded anti-vehicle weapons, at best resorting to grenade-launchers, but these seem to be anti-infantry weapons and not very effective against vehicles.
Conversely, alien vehicles are frequently observed being successfully engaged by Human soldiers wielding anti-armor weapons. Partially this is due to the fact that alien vehicles are based on maneuverability and not pilot safety, so they are easy to snipe, but even their unmanned drones seem to be unprepared to handle RPG attacks by infantry units. A group of marines was able to overwhelm alien aerial drones and light vehicles after they acquire several shoulder-mounted M136 AT4 anti-tank rockets from the Forward Operating base. The aliens' only counter to this is to try to deploy a greater concentration of drones, rather than switching to some kind of anti-personnel weapons.
The result is that if the aliens are robbed of their air cover, due to their local command-and-control hub being destroyed, their infantry are particularly vulnerable to air-to-ground jet strikes and assault helicopters, as well as LAV-25 vehicles.
Although the aliens make use of orbital insertion to deploy soldiers into combat zones, the full extent of their space-faring capabilities is not known. Most alien weaponry use solid projectiles that appear to be propelled electromagnetically, similar to a railgun, although their aircraft make use of a directed energy weapon.
All General Infantry soldiers use six-barreled machine guns with a mounted grenade launcher, fused directly to their right arm. These weapons use incendiary rounds with relatively high penetration with rounds being shown to pierce metal with ease (cars, garbage dumpsters, kevlar helmets), and their grenade launchers are capable of firing multiple rockets simultaneously. Different Castes use different weapons systems, with the Officer Caste using a single-barreled weapon that trades rate of fire for precision.
At the core of each General Infantry weapon is a dense magnetic cavity, presumably serving a purpose during the firing process. On the left side of the weapon is the retracting 'magazine' slot, which holds the weapon's power cell. Two cooling fans are located on the weapon.
The aliens' naval mine is a high-explosive mine with an effective blast radius of 400 square feet. The mines are self-propelled and can be adjusted remotely to change both depth and position. They utilize high frequencies that make detection difficult.
While not actually a weapon, the ammunition sled is a mobile container that is used to resupply ground forces in the field. Ammunition sleds can be dropped from ships, while their nine thrusters allow them to be easily "floated" from one location to another. They carry six fuel cells, weighing almost 150 kg / 330.75 lbs each.
The Multipurpose Weapon is the primary weapon of the Hovercraft. It consists of a double-barreled machine gun and a grenade/rocket launcher assembly mounted on a swivel. The launcher seems to use armor-piercing rockets that are ineffective against infantry, while the machine guns use standard incendiary ammunition. Two Multipurpose Weapons are mounted on each side of the Hovercraft and are operated by Intel Caste members.
Unseen Anti-Armor Weapon
During the battle on the highway overpass, several aliens set up an anti-armor weapon that fired concentrated blasts of plasma in an arc. The weapon was able to destroy an M1 Abrams by hitting the top of the armor, but did not seem to be effective against infantry. The weapon exploded in a sizeable blast after being hit with several bullets from a Humvee-mounted machinegun, killing its operators and the Operations Caste aliens around it.
Although the known alien vehicles make use of different forms of propulsion, none are wheeled. All of their vehicles are oriented toward greater mobility, at the cost of armor. In the case of all ground vehicles, this leaves the operators almost completely exposed to enemy fire.
Although the spacecraft are never seen in detail, vessels of some kind were used to deliver invading soldiers onto Earth. The vessels that made atmospheric entry were able to adjust their trajectory in space and slow their in-atmosphere descent with thrusters.
The Walking Gun is more of an infantry support weapon/field artillery than an actual vehicle. The Gun fires 16 small, guided missiles at a single target in order to destroy cover. The gun is generally well-armored, although a shot to one of the joints staggered one until the pulse jet engines at the rear of the machine were able to right it within a minute. Each walking gun is presumably operated by one of the Intel Caste members, as they are the only ones with two grasping hands. The guns are used to support both Operations and General Infantry during a battle, and are operated by a gunner and a loader, who carries several reserve magazines for the weapon.
When using the Walking Gun, alien infantry units adopt a wedge formation with the Walking Gun in the center. This formation is intended to cover the weapon's flanks and enable infantry to lay down covering fire, pinning enemy units in place for the gun to destroy.
Although the hovercraft is armed with two Multipurpose Weapons capable of taking on squads of infantry, it does not appear to be a front line vehicle. Instead, it is relegated to supporting areas that are deemed safe. The Hovercraft uses adjustable thrusters mounted on four independently moving pads to compensate for terrain, giving it great amounts of mobility at the cost of large amounts of exposure and little armor. They also have two guns, consisting of an artillery and a machine gun.
The Wedge Ship is a type of drone aircraft, entirely reliant on a centralized command and control center to function. During the invasion of Earth, thousands of Wedge Ships are deployed with the initial waves, a few of which miss their targets and impact on the beach, destroying them. The ships take several hours from landing until they are able to participate in combat.
The Wedge Ships are highly maneuverable, using pulse jet engines to make adjustments, as well as multiple exhaust engines. These exhaust engines vary in size and all of them are located at the back of the Wedge Ship. They are equally capable of reaching speeds of mach 7 or patrolling meters from the ground for enemies. The Wedge Ship weaponry consists of a high-powered Directed-Energy Weapon, located at the front of the craft. At the back of the Wedge Ship are four extensions that are related to weapon-use. Wedge Ships also have a camera or spotlight system mounted under the front of the craft. The ships have orange-tinted computer screens under some of their panels that display lines of unclear characters, presumably related to maintenance functions.
Eight wedge ships are able to go into a saucer formation for greater protection and better firepower. They are all capable of dismantling/disabling in a matter of seconds, as well as forming together in a matter of seconds. The wedge ships use ELINT (Electronic Intelligence) to detect enemy communications and home in on the source.
Cargo Drones are used to drop supplies and reinforcements in alien-secured territory. While little is known of their capabilities, it is likely that they fill the same role as Human cargo helicopters. Cargo Drones have been seen to deploy both alien fire-teams and individual Ammunition Sleds.
The Central Hive is a large structure that serves the field headquarters for a beachhead. The Hives are deployed with each landing force and are buried in the ground once alien soldiers have secured a sizable area.
The Hives are more like mobile structures than actual vehicles. While they do have a means of lift, their propulsion is only enough to get them airborne; they must be towed from one location to another by drones. If the hive is targeted, it can use its drones as ablative armor, sacrificing them to protect itself.
The Central Hive also serves as a small airfield, as its main role is to serve as the field headquarters for a beachhead and a coastal landing invasion. At the very top of the aircraft is where the communications relay is; their orders are relayed through these towers. The connection needs to stay intact in order for the drones to function.
Invasion of Earth
- "At 04:46 Pacific Standard Time, twelve different locations across the globe were breached, in what appears to have been a coordinated attack by an unknown enemy. All breaches were along the coastline in what is a campaign of rapid dominance. This is a textbook military invasion. There are massive casualties in New York. Offensive lines are being set up in Boston, and at 13:15 Zulu Time, we lost communications with San Francisco and San Diego. Their status is unknown, but what we do know is this: we are the last offensive force on the West Coast. We cannot lose Los Angeles."
- ―Sergeant Major Glenn Devor in a military news broadcast during the very beginning of the invasion.
The aliens invade Earth on the 12th of August, 2011. Originally mistaken by the Humans to be clusters of meteors, they are soon revealed to be spacecraft which land off the coastal shorelines of twelve of the world's major population centers. Alien ground forces subsequently attack many of Earth's major cities, including Paris, London, Moscow, New York, Hong Kong, Rio de Janeiro, Hamburg and Tokyo.
The battle in Los Angeles showcases alien forces engaging armed forces of the United States of America; namely U.S. Marines, although National Guard, Air Force, and Army soldiers also see combat. The aliens are seen giving the U.S. Marines a very difficult fight, utilizing their advanced weaponry to conquer most of Los Angeles. Furthermore, alien aircraft eventually arrive and appear to easily take control of the air above LA from the U.S. Air Force. Besides their ground and large air forces, the aliens deploy a sort of command center which controls the unmanned flying drones. Within a day, the drones allow the aliens to push most of the U.S. military force out of LA, killing thousands during the engagements. However, a squad of Marines is able to destroy the command center, disabling all of the drones and depriving the aliens of their air assets. Without air support, the aliens had lost their advantage and their forces lacked the tactical co-hersion that was so dominant during the first hours of the invasion. These Marines later retreat back to a command post, and join up with thousands of reinforcements ready to try and take back Los Angeles from the alien invaders. It was speculated that it took a further 18 months to fully kill or capture all aliens that were part of the West Coast offensive force.
- Battle: Los Angeles (2011)
- TyRuben Ellingson, the conceptual designer for Battle: Los Angeles, made a few comments on the aliens in an interview with io9, stating that "[the] alien war craft and weapons are not brand new out-of-the-box machines, they've been deployed before, repaired and had parts swapped out". He also stated that "wherever these alien forces are from, it is a place of chaos. They are a desperate power who is here under high stakes circumstances, the exact nature of these themes is left a great deal to the audience's imagination".
- Given the decrepit appearance of their ships and equipment, it's possible that the aliens are looking for a new home planet, possibly due to their old home being uninhabitable because of warfare or some other cataclysm. This would explain their War of the Worlds-esque landing method, as well as their relatively low level of technological advancement for a space-faring civilization.
- Based on the documents found on the Unidentified Enemy website, it's possible that the aliens may actually be a scavenger species that integrates machinery originally created by another, more advanced native species.
- It is also hinted that the alien homeworld was lost in an apocalyptic world war. So the aliens seen in the movie could be survivors of one of the sides that fought in this war and that their current generation is a spaceship-born generation. That would explain the relatively old and worn appearance of their equipment and vehicles for a capable space-faring civilization.
- Despite the devastation caused by the aliens, many believe that humanity did not witness the full extent of the alien's military capabilities during the Invasion of Earth. It should be noted that the relatively old and worn appearance of their equipment for a weakening force at their homeworld makes it clear that this is not the best they have, that the equipment that their supreme powers have there can be much more powerful. The relatively compact, maneuverable equipment of the invading force, along with their rapid domination-liked doctrine also suggests that this force may be just an expeditionary force that serves to create and secure a beachhead for the the stronger (and more bulky) units followed, once the capture and consolidation was completed.