Henderson was born in Jersey in 1854, the son of the first headmaster of Victoria College, the Rev William Henderson, and Jane Melville Dalyell. Educated at Leeds Grammar School, of which his father, afterwards Dean of Carlisle, was headmaster, he was early attracted to the study of history, and obtained a scholarship at St John's College, Oxford. But he soon left the University for Sandhurst, from where he was commissioned into the 84th Foot in 1878.
After a few months service in India, he was promoted to the rank of lieutenant and returned to England, and in 1882 he went on active service to Egypt, fighting in the battles of Kassassin and Tel el-Kebir. During this time, he received numerous citations for bravery in combat, being promoted to captain in 1886.
In 1885 he was seconded to the Ordnance Store Department. In 1889 his first work, The Campaign of Fredericksburg, was published anonymously. In the same year he became Instructor in Tactics, Military Law and Administration at Sandhurst. From this post he proceeded as Professor of Military Art and History to the Staff College (1892–1899), and there exercised a profound influence on the younger generation of officers. The result of eight years work, his masterpiece: Stonewall Jackson and the American Civil War was published in 1898.
Later life and death
In the Second Boer War Lieutenant Colonel Henderson served with distinction on the staff of Lord Roberts as Director of Intelligence. But overwork and malaria broke his health, and he had to return home in January 1902, being eventually selected to write the official history of the war. Failing health obliged him to go to Egypt, where he died at Assuan on 5 March 1903.
The Very Rev William George Henderson (1819 – 24 September 1905) was Dean of Carlisle from 1884 to his death in 1905. He was educated at Magdalen College, Oxford, and ordained in 1859 after spells as a Fellow of his old college and a Tutor at Durham University and later principal of Hatfield College, Durham. He was then Headmaster of Victoria College, Jersey, and Leeds Grammar School before his appointment to the Carlisle Deanery. He died on 24 September 1905.
Col Henderson’s younger brother Ralph, also born in Jersey, followed his brother into the Army and played cricket for the Royal Military College Sandhurst against the Royal Military Academy Woolwich in July 1879. He opened the batting and was out without scoring. However, he took four wickets in each of the Woolwich Academy’s innings and his side won by an innings and 47 runs. He went on to serve in the 96th Regiment of Foot. His son Ralph Anstruther Henderson had a distinguished military career, reaching the rank of Brigadier.
Another younger brother, Charles (1866-1935) , born in Yorkshire after the family had left Jersey, rose to Admiral in the Royal Navy. Henderson was appointed Commander on 30 June 1901, Captain on 31 December 1906 and was given command of HMS Crescent on 22 October 1907. On 2 October 1917 he was appointed Captain of the Dockyard and Deputy Superintendent and King's Harbour Master at Rosyth Royal Dockyard He was promoted to Rear-Admiral on 25 August, 1918 and placed on the Retired List at his own request the following day. His future in the Navy had been decided at a meeting of the Board of Admiralty on 15 June, when all five Sea Lords voted that he be retired on promotion to Flag Rank.
He was promoted to Vice-Admiral on the Retired List on 1 November 1923 and advanced to the rank of Admiral on the Retired List on 1 August 1927.