Anati

The Anati are a race that was targeted for enslavement by the Yeerk Empire. Visser One was responsible for the invasion by sending in a Yeerk Fleet to capture the Anati Homeworld inorder to redeem herself. The Yeerk Fleet was suppose to establish a dracon cannon installation around the Anati Homeworld to deter Andalite retaliation. Luckily the Animorphs managed to inform the Andalite high command of the invasion. The Yeerk invasion force then vanished however without a trace, and Visser One one held responsible which led to Visser One's execution.

Source

 * Visser by K.A. Applegate (1999)
 * The Test by K.A. Applegate (2000)