It was first used by the new generation of Advanced Recon Commands, to whom they used experimental version of armor, in addition to demonstrating it in Kamino for Clone Cadet Training.
Phase 2 armor began to develop during the middle of the Clone Wars era when the Republic needed more Clone Troopers for combat, as well as better way to reduce the number of casualties caused by those who originally used set of Phase 1 defective armor.
