The Thunderclap was a Rendili Hyperworks BT-7 Thunderclap class ship built especially for Republic SpecForce troopers around 3,643 BBY, during the time of the Old Republic. The ship contained just about everything a trooper could have in his barracks. At somepoint during it's time with Havoc Squad, the ship crash-landed and was abandoned on the planet Saleucami, where it rested for around three thousand years.
However, in 21 BBY, during the search for General Grievous on Saleucami, an Alpha-class ARC Trooper , Alpha-144, nicknamed "Dogma" and his legion, the 666th Legion, discovered the Thunderclap, abandoned, in a field. Dogma immediately knew he would like the ship, so he ordered a squad to repair the Thunderclap so he could give it a test run. It worked beautifully once Dogma started up the ship. He was surprised that the ship still ran fine after 3,000 years in a field. The Thunderclap went on to become Dogma's personal ship for the rest of the Clone Wars, the Rebellion, and the New Jedi Order.