16 June 1779: Spain declares war on Great Britain

The Great Siege of Gibraltar, the longest siege ever endured by the British Armed Forces, began after Spain officially declared war on Great Britain on 16 June, 1779.

The siege was an unsuccessful attempt by Spain and France to capture Gibraltar from the British during the American War of Independence (1775 -1783). The war began as a conflict between Great Britain and its North American colonies, but by 1779 both Spain and France had offered their allegiance to America.

France had already declared war on Britain in 1778, and in April 1779, they, along with Spain, signed the Treaty of Aranjuez.

Spain declared war on Great Britain in 1779 and, together with France, set about recovering lost territory. Spain's main goal, as it was in the Seven Years' War, was the recovery of Gibraltar and Minorca, the latter they took with relative ease.

Gibraltar, which was crucial in Britain's control of the Mediterranean Sea, would prove impossible to conquer.

The Rock had been a British Overseas Colony since 1704, and its defence during the siege was down to the expertise of George Augustus Eliott, a British officer who had served in three major wars during the eighteenth century.

Eliott had been appointed Governor of Gibraltar in 1777 and during the assault he used his engineering skills to good effect in improving the fortifications. He was a self-restrained man - his diet comprising vegetables, biscuits and water - who rarely slept for more than four hours at a time.

Spain expected the capture of Gibraltar to be relatively quick, but the British had anticipated an attack for some time, and a number of ships had sailed to reinforce the Rock.

Although the Spanish deployed a blockade of Gibraltar in order to starve the garrison, the British were able to hold out in the fortress, receiving occasional supplies that were smuggled in by sea.

The Siege of Gibraltar was to last three years and seven months, yet despite the greater strength of the besieging Franco-Spanish forces - around 33,000 - the British managed to defend the Rock under great duress. In September 1782, the Spanish and French armies initiated a grand attack, involving 48 ships, but the garrison held its position and by 1783, the siege was over. The British Parliament sent their official thanks to Eliott and he was nominated a Knight of the Bath, an honour invested on him at Gibraltar on 23 April 1783.

Eliott returned to England in 1787, where he was given the title Lord Heathfield, Baron Heathfield of Gibraltar. In recognition of his outstanding achievement, many statues and portraits were produced in his honour. A portrait titled The Installation Supper, which resides in the National Portrait Gallery, was painted by the British caricaturist James Gillray in 1778.

Eliott died in Germany while returning to Gibraltar in 1790. There is a bust of Eliott in the Botanic Gardens in Gibraltar.