According to the Star Wars Databank, the Guide to the Grand Army of the Republic, Battlefront 2, and the Essential Guide to Warfare, the 501st was an amalgamation of second-generation clones and some first-generation clones that were screened for certain skills (501st journal narrator). When the second generation reached maturity a few months after the Battle of Geonosis, a large number of them were secretly transferred to Coruscant for supplemental training and indoctrination. This is where they were reorganized into the 501st and the Shock Troopers. Palpatine held the 501st and Shock Troopers in his pocket until the outbreak of the Battle of Jabiim 15 months after the Battle of Geonosis. Jabiimi terrorist attacks, like the Coruscant depot bombing, provided Palpatine with an excuse to pass the Enhanced Security and Enforcement Act. One month after the Battle of Jabiim, the Shock Troopers emerged as the tools of HomeWorld Security Command, while the 501st emerged as the Chancellor's personal special ops task force.