Henry Jackson was born on 21st January 1855. He entered the Royal Navy at the age of thirteen in 1868 but was more interested in the scientific aspects and at first specialised in navigation. From 1878 to 1879, he was a junior Lieutenant on HMS Active. In 1881, he was appointed to HMS Vernon, the torpedo school ship at Portsmouth. It was here that he became interested in the mechanism of the torpedo, and he qualified as a Torpedo Lieutenant and served at HMS Vernon for three and a half years after qualifying.
In January 1890, he was promoted Commander, and in the same year began experimenting with radio waves. However, opportunities to experiment were few and progress was very slow. In 1895, while in command of HMS Defiance he transmitted a signal the length of his ship, and in the following year, succeeded in transmitting signals over a distance of several hundred yards.
Soon after his promotion to Captain in June 1896, Jackson met Guglielmo Marconi at a conference at the War Office and discovered that they had both been working along similar lines. Although Marconi was aiming at long distance wireless communication over land and sea, and Jackson's objective was to improve the efficiency of communications for the fleet, they began working together. In 1900, their efforts were rewarded when the Admiralty placed contracts for the supply of Marconi radio equipment to ships of the navy. In recognition of his work in this field, Jackson was elected a Fellow of the Royal Society in 1901. The following year, he wrote a paper for the Society entitled: On some phenomena affecting the transmission of electric waves over the surface of the sea and earth, which described signalling experiments at sea over distances of 140 nautical miles and how intervening land reduced the signalling range between two ships. Jackson also observed the effect of lightning flashes, noting that whenever electrical disturbances were present in the atmosphere, the travel of the wireless waves was affected and reduced the strength of the signal by between 30% and 80%.
In 1902, Jackson was appointed Assistant Director of Torpedoes at the Admiralty, and in 1904 returned to HMS Vernon as Captain.
Jackson was appointed President of the Royal Naval College at Greenwich and created Knight Grand Cross of the Order of the Bath. From 1917 to 1919, he was also First and Principal Naval Aide-de-Camp to King George V. Jackson remained at Greenwich until July 1919 when he was advanced to the rank of Admiral of the Fleet.
In 1920 he was appointed as the first Chairman of the Radio Research Board of the Department of Scientific and Industrial Research. This post enabled him to undertake further experimental work in wireless telegraphy. Under his direction, experiments were carried out dealing with the propagation of wireless waves, the nature of atmospherics, radio direction-finding, and precise radio frequency measurements. In 1924, Jackson retired from the Navy. While in retirement, Jackson was awarded the Hughes Medal by the Royal Society in 1926, recognising his work on wireless telegraphy. He was appointed Secretary, and later, Chairman, of the British National Committee on Radio Telegraphy.
During his life, he received honorary degrees from the Universities of Oxford, Cambridge and Leeds. During his naval career, he had also won many foreign awards, including the Grand Cross of the Spanish Order of Naval Merit, the Japanese Order of the Rising Sun, and the Russian Order of the White Eagle (1st class), and he was a Grand Officer of the French Legion of Honour. He was a member of the Institution of Electrical Engineers, Honorary Vice-President of the Institution of Naval Architects, and also Vice-President of the Seamenís Hospital Society.