When and what is Trafalgar Day?


Visitors to London inevitably end up at Trafalgar Square, and these visitors all take pictures of the tall column that honours Lord Horatio Nelson (1758-1805).
Nelson, “The Hero of Trafalgar,” lost his life in that battle during the Napoleonic Wars. The combined French and Spanish fleets were defeated off the coast of Cape Gibraltar on October 21, 1805. This ended Napoleon’s scheme to decoy the Royal Navy away from the English Channel, allowing him to invade England without naval interference.
October 21 is still known as Trafalgar Day throughout the Commonwealth. In Canada, these days, Trafalgar Day celebrations are usually observed only by the Royal Canadian Navy. When it is noted by a larger number of people, as it will be in Regina this year, it’s deferred to the Saturday following the 21st. 
Still, Nelson left his mark on our country albeit not as pronounced a mark as one might expect given the numerous place names called Nelson.
Very few of these places commemorate the great vice-admiral. Manitoba alone has 13 Nelsons including Nelson Island, Nelson Creek, Nelson Rapids and, of course, the mighty Nelson River. Alas! Only Nelson Lake is called after the Hero of Trafalgar. The river was named by Thomas Button in memory of his sailing master, Francis Nelson, who is buried on the river bank.
B.C. does somewhat better. Although the city of Nelson is not named for Lord Nelson, Fort Nelson, located at Mile 300 on the Alaska Highway, is. So is Nelson Island.
There’s a Nelson-Miramichi commemorating Lord Nelson in New Brunswick, and a Trafalgar Township in Ontario. Trafalgar Township, now part of the city of Oakville, was named in 1806, only one year after the battle.
New Zealand has a city called after Nelson, and there’s another in England — in Lancashire.
Haydn’s Mass Number 11 in D Minor, known as Nelson’s Mass, was probably named in commemoration of an earlier Nelson victory, at Aboukir Bay (1798).
Most people who visit Trafalgar Square are unconcerned about all this. They’re more likely to notice the ever-present pigeons that defecate all over Nelson’s Column.
Nelson gained popularity as a given name following the Battle of Trafalgar. The surname Nelson (Neilson) means “son of Neil.” A common name in all English-speaking countries, it can be traced back to the royal house of Tara in Ireland. The spelling Nelson is more common in England, while Neilson and MacNeil (McNeil) are mostly found in Ireland and Scotland.
Trafalgar takes its name from Cape Trafalgar on the southwestern coast of Spain. Trafalgar is Arabic in origin, although its meaning is uncertain. It has been suggested that Trafalgar comes from taraf al-agarr (end of the column). If so, the reference is to the Pillars of Hercules, two promontories at the far eastern end of the Strait of Gibraltar. According to legend, the Pillars were erected by Hercules himself.
Trafalgar Square, London’s most famous square, was planned and laid-out between 1829 and 1841 and named for the battle. The Nelson Column was erected in 1842.
Horatio, from the Roman clan name Horatius, has an obscure meaning.