Henry Seymour Rawlinson, born in 1864, was the elder son of Sir Henry Creswicke Rawlinson (1st Baronet) and educated at Eton College. He entered the Royal Military College, Sandhurst, and then served in India and Burma [later Myanmar].

In 1892 he entered the Staff College, Camberley, going to Aldershot in 1895 with the rank of brigade major. In January 1898 he was appointed Staff Officer to General Kitchener at the time of Khartoum (Sudan campaign). He subsequently took up an appointment in South Africa and was besieged in Ladysmith. After the relief of Ladysmith in March 1900 he was appointed to the staff of 1st Earl (Frederick) Roberts, and Kitchener. In 1902 he was posted to the Department of Education at the War Office, then appointed commandant of the Staff College and subsequently given command of 2nd [infantry] Brigade at Aldershot. He was then promoted to the rank of Major-General and given command of 3rd Division, Salisbury Plain. On the outbreak of World War One he was appointed director of recruiting at the War Office, again under Kitchener. In October 1914 he was given command of a division helping in the defence of Antwerp. After the fall of Antwerp his force was withdrawn to the west of Belgium to join the main British Expeditionary Force. He was placed in command of the 4th Corps and was involved in the Battle of Ypres. He was given temporary command of the 1st Army and from January 1916 of the new 4th Army. This army was given a major role in the British offensive at the Somme from July 1916 and after the Somme campaign he was promoted to full general. In February 1918 he was appointed British representative on the executive war board of the Supreme War Council.

After World War One his commands included a stint in 1919 in north Russia to evacuate British troops engaged in aiding anti-Bolshevik forces and in August 1920 he was appointed Commander-in-Chief in India. He died in India in March 1925

He was awarded GCB 1919, GCSI 1924, GCVO 1917 and KCMG 1918. He was created Baron Rawlinson of Trent in 1919.