Dannatt took command of 3rd Mechanised Division in 1999 and simultaneously commanded British forces in Kosovo. After a brief tour in Bosnia, he was appointed Assistant Chief of the General Staff (ACGS). Following the attacks of 11 September 2001, he became involved in planning for subsequent operations in the Middle East. As Commander of the Allied Rapid Reaction Corps (ARRC), a role he assumed in 2003, Dannatt led the ARRC headquarters in planning for deployments to Iraq and Afghanistan. The ARRC served in Afghanistan in 2005, but by this time Dannatt was Commander-in-Chief, Land Command—the day-to-day commander of the British Army. He was responsible for implementing a controversial reorganisation of the infantry which eventually resulted in his regiment, the Green Howards, being amalgamated into the Yorkshire Regiment.