Brigade-Major Charles Harrison was born circa 1783 and appointed Ensign (by purchase) in the 32nd Regiment of Foot on 21.1.1804. He became Lieutenant (without purchase) in the 53rd Foot in 1805 and, following active service in the Peninsula, Captain in 1813. In 1815 he accompanied his regiment to St. Helena and there was at once appointed Brigade-Major under 'Napoleon's gaoler' Sir Hudson Lowe. In this capacity he became well acquainted with the Emperor and members of his entourage. In December 1816 Napoleon's confidante the Comte de Las Casas was lodged with Harrison at the Hut's Gate (a cottage near the Emperor's residence, Longwood House) following that nobleman's arrest 'for corrupting the fidelity of an inhabitant of the island, so far as to render him, in a criminal and underhand way, the bearer of secret and clandestine letters for Europe'. In 1819, whilst Comte de Montholon was kept from his duties by sickness, Sir Hudson Lowe, 'ingenious in inventing new vexations', refused to correspond with Napoleon's most loyal aide General Bertrand, and insisted 'upon having a direct correspondence with the Emperor, either by the visit of one of his officers twice a day to him, or by letter ... To attain this he sent Sir Thomas Reade or Major Harrison to Longwood, who entered the house, proceeded to the outer door of Napoleon's apartments, against which they continued to knock for sometime, exclaiming, "Come out, Napoleon Bonaparte!" - "We want Napoleon Bonaparte!" &c.; concluding this scene of uncalled for outrage by leaving behind the packets of letters addressed to 'Napoleon Bonaparte'.'

On 29.3.1821 Harrison became Captain of the 20th Regiment of Foot, and was still serving as Brigade-Major when the Emperor died within a few minutes of six o'clock on 5.5.1821. Next day Harrison, together with Captain William Crokat and seven doctors, attended the Emperor's post-mortem as the officially appointed British witnesses - the post mortem itself being carried out by two Corsicans, Dr. Antomarchi and the Abbe Vignalis, on the billiard table at Longwood at 2 p.m. The French were represented by the Counts Bertrand, Montholon, Marchand and St. Denis. The cause of the Emperor's death was officially given to be cancer of the stomach, though the French maintained that he had contracted gastro-hepatitis during his confined stay on St. Helena. On 23.10.1823 Harrison exchanged back into the 53rd, and became Major (Unattached) in 1826 prior to his apparent retirement from the Army in 1838. With Assistant-Commissary-General Denzil Ibbetson and Lieutenants Mathias and Hutchins, Harrison shared the distinction of being one of the four British Officers present on the Island during 'the whole of the captivity'.