Complex sentence: Even after he defected to the Rebel Alliance, the Storm Commando training programme still continued, and only the best Imperial Stormtroopers received this training and they were rare by the end of the war.
Split into simpler sentences: Even after he defected to the Rebel Alliance, the Storm Commando training programme still continued. Only the best Imperial Stormtroopers received this training and they were rare by the end of the war.