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c. 32 BBY
Stealth Ship Crew
Spark, born CT-1284, was a Special operations clone trooper who served in the Grand Army of the Republic or more precisely, in the 7th Sky Corps, under the command of Jedi general Obi-Wan Kenobi, during the Clone Wars under the command of Commander Blackout, as he was still new to the action, he was often called a "Shiny" as most younger, inexperienced clone's were called, because their armor was still shiny, from lack of use in battle.
During a stealth mission in 22 BBY, to use a stealth ship to get past Separatist blockades guarding Christophisis, and deliver supplies to it's inhabitants. After one of the crew members was injured, Spark, a shiny, was told to take his place, throughout the whole mission, his Commander, Blackout took over the station next to him, and acted as his mentor. The Separatist admiral controlling the blockade, Admiral Trench thought that the Grand Army of the Republic could not stand it if Christophsis was attacked, so he sent bombers to attack a command post on Christophsis.
The Republic then changed direction and opened fire on Trench's ship launching torpedoes, which proved useless against the Separatist ship, due to it's strong thermal shields. Anakin Skywalker, the Republic ship's pilot, forced Trench to fire his own torpedoes, then Skywalker ordered the Steal Troopers to put all of the ship's power to the engines, he then flew at Trench’s ship, then as the stealth ship slid off, causing the torpedoes to explode, destroying Trench's flagship. Spark and his fellow troopers then were able to deliver the supplies, Blackout then informed Spark that he was no longer a shiny, and was part of the crew.
Although Spark is never confirmed to be in the Third Army, it is very obvious. Spark is under the command of Jedi General Obi-Wan Kenobi, proving that he has to serve somewhere within the Third Systems Army.