General Sir William Thwaites, KCB, KCMG (9 June 1868 – 22 June 1947) was a British Army officer who served as commander of the British Army of the Rhine.^[1]

Thwaites was born in Kensington, the son of William Thwaites of Durham Villas. He was educated at Wellington College, Berkshire and at Heidelberg before passing into the Royal Military Academy, Woolwich.^[1][2]

Thwaites was commissioned into the Royal Artillery in 1887.^[3]

He was promoted to lieutenant on 16 February 1890 and to captain on 10 October 1897.^[4] He served in the Second Boer War 1899–1900 as an Adjutant in 33rd Brigade Royal Field Artillery,^[3] and took part in operations in Natal in late 1899, including engagements at Rietfontein and Lombard′s Knop and the defence of Ladysmith. For his service he was mentioned in despatches.^[4] Following his return to the United Kingdom, he served as divisional adjutant in Kildare until late 1902,^[5][6] after he was promoted to major on 20 August 1902.^[7]

He served in the First World War on the Western Front in France and Belgium. After being promoted to the temporary rank of brigadier general in June 1915, he took command of the 141st (5th London) Brigade, taking over from its previous commander, George Colborne Nugent, who had been killed.^[8] He was then promoted to the temporary rank of major general^[9] and made general officer commanding (GOC) of the 46th (North Midland) Division in July 1916.^[3] He was appointed a Companion of the Order of the Bath (CB) in January 1917.^[10] His major general's rank became substantive in June 1918.^[11]

After the war Thwaites became director of military intelligence at the War Office from 1918, and then director of military operations and intelligence from 1922.^[3] In 1923 he became GOC 47th (2nd London) Division and, after being promoted to lieutenant general in October 1926,^[12] was in 1927 appointed general officer commanding-in-chief (GOC-in-C) British Army of the Rhine (BAOR):^[3] he was the last person to hold this post until after the Second World War.^[13] He was Director General of the Territorial Army (TA) from 1931 to 1933,^[3] and retired from the army on 1 October 1933, when he was appointed an extra aide-de-camp general to King George V.^[14]

• Davies, Frank; Maddocks, Graham (2014) [1995]. Bloody Red Tabs: General Officer Casualties of the Great War 1914–1918. Pen and Sword Books. ISBN 978-1-78346-237-7.