BBY/ABY is used to position items along the Star Wars Timeline. BBY refers to Before the Battle of Yavin. ABY refers to After the Battle of Yavin. The Battle of Yavin in Episode IV: A New Hope occured in 0 BBY/ABY.
Obi-Wan and Anakin command a battalion of clone troopers in a losing battlefront of the Clone Wars. Anakin teams up with a crew of masterless Padawans whose Jedi mentors have died in battle, as well as with A'Sharad Hett, who took Anakin under his wing to help him come to grips with the reality of death. This backfires tremendously of course, because Anakin hates Tusken Raiders. It showcases the brutality and realism of the darker side of war in a way that only the Dark Horse Republic comics could achieve.
General Obi-Wan Kenobi and his Padawan Anakin Skywalker find themselves in command of a regiment of Clone Troopers on the muddy battlefields of the rain world of Jabiim. With their supply lines stretched thin and reinforcements unable to land due to the perpetual storms, the Jedi and their army have become easy targets for the rebel Alto Stratus and his elite Nimbus warriors. The situation goes from bad to worse when General Kenobi is listed missing in action, and Anakin is teamed with a group of other masterless young Jedi on a doomed mission to hold the last line in the Republic's defense!