Since the founding of the Republic the Generals and the Senate knew they needed an elite corp of men and women to serve and protect sanctity of this new found unity of worlds. Born from the ashes of battlefields of long forgotten conflicts these members sought to make their Galaxy a place to be proud of.
Evocatus (plural Evocati) was the term for a soldier in the army who had served out his/her time and obtained a discharge but had voluntarily enlisted again at the invitation of their commander.
There has always existed a considerable number of evocati in every army of importance, and when the General was a favorite among the soldiers. the number of veterans who joined his/her standard naturally increased.
Serving as Commanders of Battalions, Brigades, Squadrons and Recon Detachments these veterans found their way moving up the chain and some serve as Generals themselves.
To be named as a member of the Evocati is the highest honor one can be bestowed, and to bare the name one must be quite the soldier.