The Australian 1st Division was raised during the initial formation of the Australian Imperial Force (AIF) on 15 August 1914, shortly after the outbreak of the First World War. The division consisted of around 18,000 men, organised into three infantry brigades, each of four battalions, and various supporting units including artillery, light horse, engineers and medical personnel. Each infantry battalion initially consisted of eight companies, although in January 1915, they were reorganised into the British four-company system. Its first commander was the senior Australian general and head of the AIF, Major General William Bridges. Over the course of six weeks, the division's subordinate units were raised separately in the various states before embarking overseas. The transports then concentrated off the Western Australian coast and the combined fleet sailed for Britain. While en route, concerns about overcrowding in the training camps in the United Kingdom meant that the decision was made to land the division in Egypt, where it would complete its training before being transported to the Western Front.