William Garnett Braithwaite, a senior officer in the New Zealand Division in the First World War, was born on 21 October 1870 at Kendal, Westmorland, England. He was the son of Garnett Braithwaite, gentleman, and his wife, Elizabeth Mary Kay. Educated at Marlborough College and the Royal Military College, Sandhurst, Braithwaite entered the British Army in 1891, rising to the rank of captain in 1899. He served in the South African War from 1899 to 1902. On 14 August 1901 he married Gwendolen Elizabeth Hewett at Stoke, Devonport, England; they were to have two daughters and one son.
By 1910 Braithwaite had risen to the rank of major in the Royal Welsh Fusiliers. In July 1911 he arrived in Wellington, New Zealand, as a general staff officer with Major General Alexander Godley, newly appointed commandant of the New Zealand Defence Forces. Braithwaite became GSO of the Auckland Military District, and was given the temporary rank of lieutenant colonel in February 1913. A little over a year later he was appointed chief of the general staff and director of staff duties and military training. His responsibilities included staff organisation, officer education, training, plans for local defence, and war organisation and mobilisation. It was a demanding post, but one that Braithwaite was only to occupy briefly. After the outbreak of hostilities in Europe, he left New Zealand on 14 August 1914. Gwendolen Braithwaite moved with the children to her mother's house in Devonport, England.
Braithwaite now became principal operations officer with the New Zealand Expeditionary Force. After a period in Egypt he embarked for the Dardanelles as general staff officer (grade I) in New Zealand Divisional Headquarters. Godley, the division's commander, had a preference for professional staff, and Braithwaite did nothing to hurt his prospects. He was well regarded by his commander, and his diary reveals a perceptive staff officer. He was twice mentioned in dispatches in August. With the number of casualties on Gallipoli mounting, Braithwaite found himself briefly in command of the New Zealand Infantry Brigade on two occasions. He became ill and was evacuated on 19 September, returning to duty in late October. He arrived back in Gallipoli to command the New Zealand Infantry Brigade headquarters on 17 November.
After the evacuation to Egypt, Braithwaite was given command of the New Zealand Rifle Brigade in December 1915 and made a temporary brigadier general, and substantive lieutenant colonel. He was appointed a CMG on 1 January 1916 and took command of the 2nd New Zealand Infantry Brigade on 1 March. He left Egypt in early April, and soon rejoined his new command in France, where he was entrusted with temporary command of the New Zealand Division on 6 May when Major General A. H. Russell went on leave. Braithwaite steadily built up a rapport with Russell, establishing himself as one of the division's two best brigadiers.
When the division was added to the Somme offensive, Braithwaite's brigade was given the task of capturing enemy positions near Flers. It sustained some 700 casualties in taking the Switch trench on 15 September 1916. On 30 November Braithwaite was awarded the Serbian Order of the White Eagle (third class).
Promoted to brevet colonel 'for distinguished service in the field' on 3 June 1917, Braithwaite was given a central role in the attack on Messines (Mesen) on 7 June. Tactically adept, and taking into account the harsh lessons of the Somme, Braithwaite's attacks were skilfully executed. Messines was rapidly captured by the division with little loss to his brigade.
In the battle of Passchendaele (Passendale) in October 1917, the brigade's task was to renew an attack on the Bellevue Spur. On 12 October it went in over the sodden, shell-cratered, open terrain. There was a savage reverse. The German wire had not been cut, and Braithwaite's battalions disintegrated. On receiving orders to renew the assault, Braithwaite signalled to Russell that it was 'impossible for this Brigade to continue the attack without incurring abnormal additional losses', and refused to order a further advance. He was far more concerned with recovering the wounded. In all, the brigade lost some 1,500 men.
By this time Braithwaite was the last of the early brigadiers in the division. With the exacting pressure Russell maintained on the division's officers, it is scarcely surprising that he was on the point of nervous collapse. On 24 October he again stood in for Russell as temporary divisional commander. Shortly after operations at Polderhoek he was hospitalised, then evacuated ill to England on 27 December. He was burnt-out.
Braithwaite did not return to the NZEF. Instead, he was appointed to the post of brigadier general staff, to a British corps on 11 February 1918, and was back on the books of his old regiment, the Royal Welsh Fusiliers. On 3 June he received a CB. He retired in 1925, and died at Camberley, Surrey, on 15 October 1937; the date of his wife's death is not known.
William Braithwaite was a very good staff officer and a competent brigade commander. Highly energetic, he demanded high standards and results; he refused to countenance indiscipline, slackness, or indecision. Not courting popularity, he constantly looked after the interests of his men and was one of the few commanders that most soldiers looked on with affectionate regard. He was a significant force in reorganising New Zealand's armed forces before the war, and in the shaping of the expeditionary force.