On 18 July 1943, Robertson arrived in Sicily with his Tripbase headquarters, which now became known as Fortbase (Forward Tripolitania Base). Fortbase was responsible for the ports and beaches in Eastern Sicily, for coordinating demands for shipping, and for mounting the Eighth Army units for the Allied invasion of Italy. From a doctrinal point of view, Fortbase usurped administrative functions that would normally have been carried out by Alexander's 15th Army Group, where Miller was now the Chief Administrative Officer, but most of the British units in Sicily had formed part of the Eighth Army, and were accustomed to its methods. Fortbase was officially under the command of 15th Army Group, but Montgomery treated it as part of the Eighth Army. Robertson also had to deal with General Dwight Eisenhower's Allied Forces Headquarters, (AFHQ), where Major General Humfrey Gale was the Chief Administrative Officer. At the same time, he also had to deal with GHQ Middle East, although it was not under AFHQ, because most of the Eighth Army's support still derived from there. Starting on 20 August, ships began arriving direct from the United Kingdom and the United States, but this created more problems, as convoys carried stores that had been ordered weeks before, and congested the ports by unloading stores that were in excess of requirements or not required at all. De Guingand credited Robertson's success in organising Fortbase as a major factor in the Eighth Army being able to accelerate its advance and link up with the United States Fifth Army when the latter ran into trouble at Salerno.