Summerhayes joined World War I as a medical officer in the RAMC, and rose in rank to commanded the South Midland Field Ambulance as the
lieutenant colonel of his team. He was a part of the 4th Battalion Oxfordshire & Buckinghamshire Light Infantry in France and Italy. He received the
Territorial Decoration in the 1st South Midland Field Ambulance from the King on 12 October 1920.
Ranks • Captain in the Baluchistan Volunteer Rifles [in India] • Lieutenant in the 4th Battalion, the
Oxfordshire and Buckinghamshire Light Infantry, on 1 June 1909 • Lieutenant in Notts and Derby Field Ambulance, Royal Army Medical Corps on 8 February 1913 • Captain in RAMC on 6 December 1914 • Major in RAMC on 25 April 1915 • Acting Lieutenant Colonel on 22 May 1918 – 20 March 1919
POWs • Summerhayes was recognized in the Western Times, a British newspaper, in 1918 as the
British Red Cross Mission chief for the treatment of
prisoners of war (POWs). • In Austria where he was stationed, he revealed the bleak prospects of the people there due to
starvation, bringing attention to the need for assistance. • He was employed on similar military missions for POWs in
Hungary,
Czechoslovakia, and
Silesia.
Military escort to Charles I After the end of WWI, Summerhayes was chosen to protect the last Austrian-Hungarian Emperor
Charles I in Ekartsau, replacing the first military escort
Sir Thomas Montgomery-Cuninghame, 10th Baronet. He was assigned to his role by
King George V of the
United Kingdom after working in
Germany and
Austria to lead prisoners-of-war out of their countries. Emperor Charles I wrote a letter to King George thanking him for sending Colonel Summerhayes for his protection. The last royal Austrian-Hungarian family was provided these escorts because socialist regimes were taking over Vienna, Austria after WWI and there was fear of a potential assassination. He wrote that Summerhayes was charming and fulfills his duty as a virtuous and clever man. Furthermore, Summerhayes' cheerful character was able to brighten the mood of the royal family during their stay in
Eckartsau, providing emotional and medical support. Summerhayes was replaced by
Edward Lisle Strutt, another
British Army Colonel, as protector to emperor. After serving as the second escort to Charles, Summerhayes was then sent to accompany
Archduke Felix, the fourth child of Charles I, to
Switzerland to monitor his health. ==British Medical Association==