Deal is first mentioned as a village in the Domesday Book of 1086, where it appears as Addelam. Deal developed into a port by the end of the 13th century. In 1495, the town was the site of an attempted landing by the pretender to the English throne Perkin Warbeck. His supporters were driven off by locals loyal to Henry VII at the Battle of Deal. Deal, Walmer and Sandown (now a ruin) castles were constructed around the town by Henry VIII to protect against foreign naval attack. A timber walkway behind the shingle banks connected all three castles. In 1861, a Royal MarinesDepot was established in the town and by 1930 was headquarters of the Royal Marine School of Music. In 1989, it was bombed by the Provisional Irish Republican Army, killing 11 bandsmen. A bandstand was erected on Walmer Green in remembrance of those who died and hosts a yearly concert by the marine band.
The Downs, the water between the town beach and the Goodwin sands, provides a naturally sheltered anchorage. On the days of sail it was common to find four or five hundred ships waiting for a change in wind direction that would allow them to proceed. One problem, however, with the Downs was the quality of the holding ground of the anchorage. It was common for ships to drag their anchors in strong winds from north /northeast and southeast, This provided salvage work as an additional source of income for the town, with many ships being saved. When the port of Sandwich silted up, the only way to provide ships in the Downs with fresh provisions was in boats launched from Deal beach. This trade lasted until steam replaced sail. The importance of the Downs declined from the 1860's, as steam replaced sail. By the 1880s, the only common usage of the anchorage was by small sailing vessels.
Deal was visited by Admiral, Lord Nelson and was the first land that James Cook set foot on in 1771, on his return from his voyage to Australia. It is alleged that Julius Caesar made his landfall on Deal beaches and a small plaque commemorates the event on The Beach green. The anchorage is still used today by international and regional shipping, though on a scale far smaller than in former times. In 1672, a small Naval Yard was established at Deal, providing stores and minor repair facilities. Just outside the gates of the yard there was a semaphore tower used as a communication link to the Admiralty in London. In 1855 it was converted to the Timeball Tower, allowing noon at Greenwich to be quickly transmitted to those ships moored in the Downs to reset their chronometers. The Deal Maritime and Local History Museum in St George's Road contains a number of displays and artefacts, relating the town's maritime, industrial, domestic and leisure history. A naval storehouse was built in Deal in 1672, providing for ships anchored in the Downs. There was also a naval victualling yard where a number of small supply boats could carry supplies, provisions, personnel or equipment, as required, to those ships anchored in the Downs. The Yard closed in 1864. The Royal Marines depots and barracks were built shortly after the outbreak of the French Revolution. From 1861 the complex served as a sizeable depot for the Royal Marines and later , in 1930, became Royal Marines School of Music. Deal has had three piers in its history. The first, built in 1838, was destroyed in gales in1857. It was replaced by an iron pier in 1864 which was destroyed in 1940 during the Second World War. The present pier was opened on 19 November 1957 by the Duke of Edinburgh.