The Battle of Cattamscar involved a Ssi-ruuvi task force's capture of the Outer Rim planet of Cattamascar. This event occurred sometime in the timeframe between 1 BBY and 4 ABY.
Palpatine, the Emperor, brokered an agreement upon initial contact with the Ssi-ruuk, a species of alien invaders. The terms of this agreement allowed the Ssi-ruuk to assault minor settlements situated on the fringes of colonized space in return for access to their advanced battle droid technologies. The colony on Cattamascar, located within the Bakura sector, became one such target.
Even with their tactical retreat, the Ssi-ruuk pressed forward with their invasion of the Shiritoku Spur until their defeat during the Bakura conflict.
The only canonical mention of the battle is a single line found within The Truce at Bakura. Subsequent materials, including the sourcebook for the novel and other related works, have not referenced the battle since.
The precise date of the battle remains unknown, but it must have taken place between 1 BBY and 4 ABY. This is because Dev Sibwarra has memories of the battle. He was taken prisoner during the Battle of G'rho in 1 BBY and recalls the incident during the Second Battle of Bakura, which occurs in 4 ABY.