In 1920, Captain Stamer was seconded for service with the Egyptian Army until 1925, from 1925 until 1930 he was attached to the Sudan Defence Force and it was not until 1930 that he rejoined the North Staffords. From 1933 to 1936 he was officer commanding the regimental depot at Lichfield and was promoted to Major in 1933 From the depot he joined the regiment's 2nd Battalion who were, in 1937, in Palestine. On Christmas Day 1937, Stamer was commander of a small force comprising two companies of his own battalion and a company of the 1st Battalion, Border Regiment on operations against Arab raiders from Syria. Stamer's force came under fire and in an engagement that lasted most of the day Stamer's men inflicted 25 to 30 casualties upon their enemies while suffering less casualties themselves. Stamer was awarded the DSO for his leadership during the engagement, and the citation read A further Mention in Despatches also arose from Stamer's involvement in the operations in Palestine during 1937–1938. Stamer was promoted to Lt-Col in December 1938 and appointed to command 1st Battalion, North Staffordshire Regiment, then stationed in India as part of the Poona Independent Brigade.
By late 1940 Stamer was seconded from command of the 1st Battalion and moved to an appointment within Middle East Command. Made an acting Colonel he was area commander for Sollum and later Benghazi, work which resulted in him being made a Commander of the Order of the British Empire in July 1941. The citation read: A temporary Colonel from May 1941, later in the year Stamer had assumed command of 161st Infantry Brigade then on garrison duties in Cyprus with the rank of temporary Brigadier. This was a short lived command as in May 1942 he was appointed command of 1st Sudan Defence Force Brigade. A further move followed shortly and Stamer was appointed to command 131st Infantry Brigade and led it at the Second Battle of El Alamein. Later in the war Stamer was Mentioned in Despatches for a third time.
Post war
Following the end of the war, Stamer was appointed to the post of General Officer Commanding British Troops in Sudan and Eritrea, with the acting rank of Major-General. A further honour upon him in the same year was to be appointed Colonel of the Regiment for the North Staffordshire Regiment, a post he held for 10 years. In 1947 he was honoured by the American government with the award of Officer of the Legion of Merit and a year later was appointed a Companion of The Most Honourable Order of the Bath. A final substantive promotion to the substantive rank of Brigadier followed in March 1948, before he retired in November 1948 with the honorary rank of Major-General.