The 56th (West Essex) Regiment of Foot was an infantry regiment in the British Army, active from 1755 to 1881. It was originally raised in Northumbria as the 58th Regiment, and renumbered the 56th the following year when two senior regiments were disbanded. It saw service in Cuba at the capture of Havana in the Seven Years' War, and was later part of the garrison during the Great Siege of Gibraltar in the American Revolutionary War. During the French Revolutionary Wars it fought in the Caribbean and then in Holland. On the outbreak of the Napoleonic Wars the 56th raised a second battalion in 1804 as part of the anti-invasion preparations; both saw service in India and in the Indian Ocean, with the first capturing Réunion and Mauritius. A third battalion was formed in the later years of the war, but was disbanded after a brief period of service in the Netherlands.

The regiment spent much of the following period on foreign garrison duties, and saw service in the later stages of the Crimean War, at the Siege of Sevastopol. It was despatched to India during the Indian Mutiny, but did not see active service. The regiment was amalgamated with the 44th (East Essex) Regiment of Foot to form the 2nd Battalion of the Essex Regiment in 1881, as part of the Childers Reforms; the Essex Regiment's lineage is currently maintained by the 1st Battalion, Royal Anglian Regiment, a mechanised infantry unit.

Following the rise of tensions in North America in 1755, the British government decided to raise ten regiments of infantry in preparation for an expected war with France. Orders for the raising of the 52nd to 61st Regiments of Foot were issued in December of that year.

One of these regiments, the 58th Regiment of Foot, was raised at Newcastle and Gateshead on 28 December 1755, under the colonelcy of Lord Charles Manners, whose commission was dated 26 December. Throughout 1756 it recruited heavily to come to its authorised establishment of ten companies, each of 78 men. On 25 December 1756, the 50th and 51st Regiments were disbanded, and all higher-numbered units redesignated, with the 58th becoming the 56th Regiment of Foot.

In April 1757 it moved to Berwick, and thence into Scotland, where it would take up garrison duties; it occupied quarters at Aberdeen in 1758 and Edinburgh in 1759. In July 1760 it returned to England, sailing from Leith to Portsmouth, and was stationed at Hilsea through 1761. On 17 December of that year, Lord Charles Manners was succeeded in the colonelcy by Colonel William Keppel.

On 4 January 1762, Britain declared war on Spain in the Seven Years' War, and began preparing for an expedition against Spanish possessions in the Caribbean. The 56th was assigned as part of the expeditionary force, and sailed from Portsmouth on 5 March, arriving off Havana on 6 June and landing the following day. The regiment numbered a total of 933 officers and men, and was brigaded with four companies of the 1st Foot and a battalion of the 60th Foot.

The main object of the force was to besiege Morro Castle, which guarded the harbour. After a long reduction, a storming party was organised and attacked on 30 July, and took the fort after a brief but violent action, in which 150 of the garrison were killed and 400 taken prisoner, with the remaining 200 dying in an attempt to escape in small boats. The regiment was granted the battle honour "The Moro" for this action.

The city surrendered on 13 August. The regiment suffered twelve deaths, with one officer and 23 men wounded, during the campaign. The 56th remained as part of the Havana garrison for the following year, until Cuba was returned to Spain by the Treaty of Paris, when it was transported to Ireland, arriving in Limerick in October 1763. The regiment moved to Dublin in May 1765, and in June 1765 the colonelcy was assigned to Lieutenant-General James Durand. He died in 1766, and was succeeded by Colonel Hunt Walsh.