Following Mountbatten's arrival, Auchinleck's India Command (which had equal status with South East Asia Command in the military hierarchy) was responsible for the internal security of India, the defence of the North West Frontier and the buildup of India as a base, including most importantly the reorganisation of the Indian Army, the training of forces destined for SEAC and the lines of communication carrying men and material to the forward areas and to China. Auchinleck made the supply of Fourteenth Army, with probably the worst lines of communication of the war, his immediate priority; as William Slim, commander of the Fourteenth Army was later to write: