Promoted to commander on 1 January 1890, Jackson became commanding officer of the torpedo school training ship HMS "Defiance" at Wearde Quay near Saltash in January 1895: at the school he established an early reputation as a pioneer of ship-to-ship wireless technology. Promoted to captain on 30 June 1896, he became the first person to achieve ship-to-ship wireless communications and demonstrated continuous communication with another vessel up to three miles away. He became naval attaché in Paris in 1897 and went on to be commanding officer of the cruiser HMS "Juno" (equipped with wireless) in July 1899 and commanding officer of the torpedo depot ship HMS "Vulcan" (also equipped with wireless) in the Mediterranean Fleet in December 1899. He worked with Marconi to develop a fleet wireless system and this achievement was recognised with his election as a Fellow of the Royal Society in 1901. He went on to be Assistant Director of Naval Ordnance at the Admiralty in February 1902, Commanding Officer of the battleship HMS "Duncan" in October 1903 and Captain of the torpedo school HMS "Vernon" in September 1904.