Hamilton was politically a Liberal. He spoke German, French and Hindustani, was considered charming, courtly and kind. He appeared frail, yet was full of energy. He was twice recommended for the Victoria cross, but on the first occasion was considered too young, and on the second too senior. He was wounded in the wrist in the First Boer War (1881) at the Battle of Majuba, leaving his left hand almost useless. His left leg was shorter than the right, as a result of a serious injury falling from a horse.
Different people came to hold differing opinions of him. Prime minister Herbert Asquith remarked that he had 'too much feather in his brain', whereas Charles Bean, war correspondent covering the Gallipoli campaign considered he had 'a breadth of mind which the army in general does not possess'. He opposed conscription and was considered less ruthless than other successful generals.
He wrote a volume of poetry and a novel contemporarily described as risqué. Works included The fighting of the future, Icarus, A jaunt on a junk, A Ballad of Hadji and A Staff officer's Scrapbook. Witing in the introduction of his Gallipoli Diary, he commented: There is nothing certain about war except that one side won't win.
Hamilton's father was Colonel Christian Monteith Hamilton, former commander of the 92nd Highlanders. His mother Corinna was the daughter of the third Viscount Gort. His mother died giving birth to his brother, Vereker. He was educated in Cheam, Surrey and then at Wellington college. His father then sent him to stay with General von Damimers, a Hanoverian who had fought against Prussia. He married Jean Muir in 1887, daughter of a Glasgow businessman.
Hamilton was filmed as part of a war documentary 'Forgotten Men' in 1934 (aged 81).
In the First Boer War he was present at the battle of Majuba, where he was injured and then taken prisoner. He returned to England to recover, where he was treated as a hero and introduced to Queen Victoria. In 1882 he was made captain and took part in the Nile expedition of 1884-1885, becoming brevet major and winning the Khedive's star. In burma 1886-1887 he became Brevet Lieutenant Colonel. In Bengal from 1890-1893 he became Colonel in 1891 together with a D.S.O.. 1893-1895 part of Chitral Expedition as military secretary to Sir George White, commander in chief of forces in India. 1895-1898 Deputy Quarter Master General in India. 1897-1898 commanded the third brigade in the Tirah Campaign, where his left arm was injured by a shell.
In the Second Boer War he was attached to the Natal Field Force as acting adjutant general and commanded the infantry at the Battle of Elandslaagte. He took part in the Battle of Wagon Hill at Ladysmith and was frequently mentioned in despatches. He was knighted in 1902, was promoted major general, received a K.C.B. and became Chief of Staff to Lord Kitchener. The war correspondent Winston Churchill told of his campaign from Bloemfontein to Pretoria in Ian Hamilton's March (London, 1900, reprinted as the second half of The Boer War), having first met Hamilton in 1897 when they sailed on the same ship. Hamilton travelled 400 miles from Bloemfontein to Pretoria fighting 10 major battles with Boer forces and fourteen minor ones, and was recommended twice for the Victoria Cross (which was considered inappropriate because of his rank).
In 1904-1905, Hamilton was the military attaché of the Indian Army serving with the Japanese army in Manchuria during the Russo-Japanese War. Amongst the several military attachés from Western countries, he was the first to arrive in Japan after the start of the war.
This military confrontation between a well-known European army and a less-familiar Asian army was the first time the tactics of entrenched positions for infantry were defended with machine guns and artillery. This was the first twentieth century war in which the technology of warfare became increasingly important, factors which came to dominate the evolution of warfare during World War I.
Hamilton wrote that cavalry was obsolete in such a conflict, though many cavalry forces were deployed in World War I by the British army. He became a supporter of non-traditional tactics such as night attacks, and the use of aircraft.
The plan to take control of the Dardanelles and open a new front in the war had been considered in various forms in 1914. In November that year, British ships shelled the outer forts, causing the magazine at Seddülbahir castle to explode. In December, a submarine entered the channel and attacked a Turkish battleship, Çannakkale. Both these events raised the hopes of the British that an easy victory might be had, but as a consequence the Turks set about laying mines through the channels to prevent ships approaching and strengthened the fortifications. On 3 January 1915 First Sea Lord, Admiral Fisher presented a plan to the War council for a joint naval and military attack, using 75,000 troops, but only if the attack could be launched immediately. By 21 January, he wrote privately to Admiral Jellicoe that he could not approve the plan unless 200,000 men were available. Churchill himself, as First Lord of the Admiralty, had initially suggested in September 1914 that the support of 50,000 men would be needed.
An attempt was made commencing 19 February to take the strait using naval power alone. For the large ships to approach and shell the forts, the mines had to be cleared. The mines could not be cleared because of inadequate minesweepers, and the ongoing shell fire from the forts. The plan had been conceived with the idea of only sending second-rate ships which were considered expendable. On 18 March the British and a squadron of French ships mounted a more determined attack, with the result that three were sunk and three disabled by undiscovered mines. There was little effect on the defenders, except to cause them to expend the majority of their ammunition. Churchill ordered admiral John de Robeck to continue the operation, but De Robeck, replacing the intended commander of the fleet, Admiral Sackville Carden (who had become ill) saw no sense in losing further ships, and withdrew. It was then decided that an invasion by troops would be required. Had the bombardment continued it is likely the defending guns would have ceased firing for lack of shells, the minesweepers could have worked effectively and the British ships could have moved in to their objectives. .
Hamilton became responsible for organising armed landings. He had no specialised landing craft, the disparate troops he had been given had no training, and supplies for the army had been packed in ways which made them difficult to access for landings. Hamilton believed that the navy would make further attacks during his landings. The navy, realising likely losses and fundamentally opposing the idea that tactical losses of ships was acceptable declined to mount another attack. The Turks had been allowed two months warning from the first serious navy attack to prepare ground defences before the follow-up ground landing could be mounted, and they used the time effectively.