At the outbreak of World War I, the Union Defence Force had realised the urgent need for air support which brought about the establishment of the South African Aviation Corps (SAAC) on 29 January 1915.
Aircraft were purchased from France (Henri Farman F-27) while the building of an airfield at Walvis Bay commenced in earnest in order to support operations against German forces in German South West Africa. By June 1915 the SAAC was deployed to its first operational airfield at Karibib in German South West Africa in support of Gen. Botha's South African ground forces. On 9 July 1915, the German forces capitulated and most of the pilots and aircraft of the SAAC were sent to Britain in support of the Imperial war effort
On conclusion of the First World War, the British Government donated surplus aircraft plus spares and sufficient equipment to provide the nucleus of a fledgling air force to each of its Dominions. As part of this donation, which was to become known as the Imperial Gift, South Africa received a total of 113 aircraft from both the British Government (100 aircraft) as well as from other sources (13 aircraft).
On the 1 February 1920 Colonel Pierre van Ryneveld was appointed as the Director Air Service with the task of forming an air force, the date is used to mark the founding of the South African Air Force. In December 1920 the South African National insignia was added to aircraft for the first time. An Orange, Green, Red and Blue roundel was added to an Avro 504K for trial purposes but the colours were found to be unsuitable and were replaced with a Green, Red, Lemon, Yellow and Blue roundel in December 1921. These colours remained until 1927 when they were replaced with the Orange, White and Blue roundels.
The first operational deployment of the newly formed Air Force was to quell internal dissent, when in 1922 a miner's strike on the Johannesburg gold mines turned violent and led to the declaration of martial law.