In the Second Boer War in South Africa he served with the Royal Horse Artillery in the Cavalry Division under the command of Sir John French, taking part in the relief of Kimberley, the operations in the Orange Free State and the Transvaal, and being present at the Battle of Diamond Hill.

In January 1902 he received the temporary rank of lieutenant-colonel when he was given command of the 30th Battalion of the Imperial Yeomanry,[3] which left Southampton for South Africa four months later.

Birch went with his brigade to France in August 1914, serving under the command of Major General Sir Edmund Allenby, in the retreat from Mons and in the First Battle of the Aisne and Ypres-Armentières.

In May 1916, the month before he was made a Companion of the Order of the Bath,[11] Haig brought him to general headquarters as artillery adviser, a post he held until the end of the war.

In 1923 he became colonel commandant of the Royal Horse Artillery, and in the same year he was appointed Master-General of the Ordnance, a post he held until 1927.