First World War Agar Stewart Allan Masterton Adamson DSO (25 December 1865 – 21 November 1929) was a Canadian soldier who married the Toronto heiress Mabel Cawthra.

His paternal grandfather was William Agar Adamson, an Anglo-Irish parson who came to Canada in 1840 and was chaplain to the Governor, Lord Sydenham.

[3] Adamson had a privileged childhood and was educated at the private Trinity College School in Port Hope, Ontario.

He was an excellent athlete, played field sports and rowed, and won the Newmarket Stakes on his own horse.

[2] In 1893, he obtained a commission as 2nd lieutenant in the Number 4 Company of the Governor General's Foot Guards, a militia regiment.

[4] After his marriage Adamson was transferred to Halifax, Nova Scotia, to serve with the 3rd (Special Service) Battalion, Royal Canadian Regiment of Infantry.

In March 1900 he used his connections to obtain a position with Lord Strathcona's Horse as a lieutenant in charge of a group of fifty soldiers who were to be sent to South Africa to replace casualties.

[7] The small group, most with little or no real military experience, traveled without incident via Liverpool and London to Cape Town.

[10] Adamson's troop saw action on 5 July 1900 at Wolve Spruit, where Sergeant Arthur Herbert Lindsay Richardson showed conspicuous bravery in rescuing a wounded man in face of a group of advancing Boers.

Unable to settle down, in late March 1902 Adamson petitioned for a command and was appointed a junior Captain in the 6th Regiment, Canadian Mounted Rifles.

In 1905, Adamson left the Senate and moved to Toronto, where he became nominal head of the Canadian franchise of the Thornton-Smith Company, a British decorating firm.

[2] With the outbreak of World War I (1914–1918) Adamson immediately went to Ottawa and volunteered to serve, despite his age of 48 and poor vision in one eye.

He used his connections to obtain a post as a captain in the Princess Patricia's Canadian Light Infantry, and reached England with this regiment in October 1914.

Adamson survived two hours in the bitterly cold water, but died a few weeks later on 21 November 1929 in London, England.