The Nelson Chequer was a specific colour-scheme adopted by vessels of the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

, modelled on that used by Admiral Horatio Nelson. It consisted of bands of black and yellow paint along the sides broken up by black gunports. Nelson, apparently, used the same style for all vessels under his command "to be distinguished with greater certainty in case of falling in with an enemy". After the Battle of Trafalgar

Battle of Trafalgar

The Battle of Trafalgar was a sea battle fought between the British Royal Navy and the combined fleets of the French Navy and Spanish Navy, during the War of the Third Coalition of the Napoleonic Wars ....

, all vessels in the Royal Navy generally sported this pattern, though it was not mandated and some captains changed it. Nelson's flag ship, HMS Victory

HMS Victory

HMS Victory is a 104-gun first-rate ship of the line of the Royal Navy, laid down in 1759 and launched in 1765. She is most famous as Lord Nelson's flagship at the Battle of Trafalgar in 1805....

, was painted with a more traditional scheme of black with yellow stripes along the level of the gunports in Chatham

Chatham Dockyard

Chatham Dockyard, located on the River Medway and of which two-thirds is in Gillingham and one third in Chatham, Kent, England, came into existence at the time when, following the Reformation, relations with the Catholic countries of Europe had worsened, leading to a requirement for additional...

 in 1800. Nelson later had the gunports painted black as well, creating the distinctive chequer pattern. In spite of Nelson's desire to differentiate vessels by means of this colouring, it was also found among vessels of other navies, including some ships of the United States Navy by the time of the War of 1812

War of 1812

The War of 1812 was a military conflict fought between the forces of the United States of America and those of the British Empire. The Americans declared war in 1812 for several reasons, including trade restrictions because of Britain's ongoing war with France, impressment of American merchant...

. It is suggested by Sam Willis in The Fighting Temeraire that the black gunports were intended to make them appear opened, and so the ship would appear more intimidating from a distance.