The regiment was led by serving officers of the Union Defence Force, while the whole of 1st South African Brigade part of the South African Overseas Expeditionary Force coming under the command of Brigadier-General Henry Lukin DSO, a previous Inspector General of the UDF.

After formation, the 3rd Regiment departed Cape Town on a number of ships between 28 August and 17 September 1915 and sailed for Great Britain.

Here they began three months of training to bring them up to combat readiness with the expectation then being they would enter the fighting in France at some point in early 1916.

However, their orders were changed at short notice towards the end of their training and on 30 December 1915 they boarded ships in Devonport and sailed for Egypt.

The regiment then served with the Brigade at Arras during April 1917 and was part of the offensive at Ypres and Passchendale in September 1917.