• Lieutenant Colonel of the Royal Marines Edward Nicolls, 1779
• Treaty of Ghent, 1814

On 5 November 1803, Nicolls took a 12 man cutting - out party in the cutter from HMS Blanche and captured the French cutter Albion from under the battery at Monte Christe in Santo Domingo. Albion had a crew of 43 men and was armed with two 4-pounder guns and six swivels. In the fighting the French captain wounded Nicolls with a pistol shot before being himself killed. The British lost two dead and two wounded, including Nicolls. In 1804 Lieutenant Nicolls led another boat assault in the capture of a French brig. In the same year of 1804 Nicolls led a landing party of Royal Marines in the siege of Dutch forces at Curaçao. Nicolls and his Marines withstood 28 consecutive days of continuous enemy assaults on their positions.

During 1807 and 1808 Captain Nicolls participated in the siege of Corfu and in a foray to Egypt. It was during this period, too, that he was honorably mentioned in dispatches for his part in the Dardanelles Operation. In 1808 he led the boat attack which captured the Italian gunboat Volpe off Corfu.

In 1809 Captain Nicolls commanded HMS Standard's marines while the ship participated in the Gunboat War. On 18 May Nicolls assisted marines and seamen under the command of Captain William Selby of Owen Glendower in the capture of the island of Anholt. In the skirmish, a Danish garrison of 170 men put up a sharp but ineffectual resistance that killed one British marine and wounded two before surrendering. Following the capture of Anholt, Captain Nicolls was briefly assigned to duty as the British military governor of the island.

During the War of 1812, Nicolls was posted to Florida as part of an attempt to recruit the Seminoles as allies against the United States. Sailing from Bermuda in the summer of 1814, the expedition Nicolls commanded stopped in Spanish Havana, where it was told not to land in Florida by the Captain General, Juan Ruiz de Apodaca. When Nicolls arrived at Pensacola, Florida, in August, the Spanish Governor, aware of the threat the Americans posed to Florida, cooperated with Nicolls, allowing him to train and drill Creek refugees. Nicolls then participated in an unsuccessful land and naval attack on Fort Bowyer on 15 September. An American force under Andrew Jackson defeated Nicolls, taking Pensacola in November, and forced Nicolls to retreat to the Apalachicola River with freed African - American slaves from Pensacola. There, Nicolls had a fort built at Prospect Bluff (some times called the British Post, later the Negro Fort, replaced still later by Fort Gadsden), and rallied Indians and refugee ex-slaves living free in Florida, recruiting the latter into a detached unit of the Corps of Colonial Marines.

At Pensacola on 29 August 1814, Nicolls issued a widely disseminated proclamation to the people of Louisiana, urging them to join forces with the British and Indian Allies against the American government.

Nicolls is mentioned in attempts to recruit Jean Lafitte to the British cause. At the Battle of New Orleans on 8 January 1815, Nicolls was attached with some of his men to the brigade commanded by Colonel William Thornton of the 85th Regiment of Foot (Bucks Volunteers). He was the senior officer of the Royal Marines and the senior ranking Major among the British land forces present at the battle. Vice Admiral Alexander Cochrane forbade Nicolls to personally take part in the fighting, fearing that mishap to Nicolls might deprive the British of their most competent officer serving with the Redstick Creeks and Seminoles. The actual battlefield command of the Royal Marines battalion brigaded with Thornton's 85th Foot went to a junior officer, Major Thomas Benjamin Adair. Nicolls's obituary in The Gentleman's Magazine and Historical Review states that "He was the senior major of all the force before New Orleans in 1815, and as such urged his right to lead the battalion of Royal Marines in the assault (as part of Thornton's Brigade), This honor was refused, on the ground that if any accident befell him there would be no other officer competent to command his Indian Army (sic); in consequence of this, he lost the decoration of the Bath, which was conferred on Major Adair, R.M., who so nobly led the battalion." On the same page it was recalled that Nicolls was still suffering from the effects of three serious wounds received in the attack on Fort Bowyer just months earlier. Nicolls never regained the use of his right eye.

On 15 March 1815, an American Army aide - de - camp named Walter Bourke communicated to Major General Thomas Pinckney that conditions were difficult on the Georgia frontier despite efforts of Brigadier General John Floyd of the Georgia militia to reinforce American defenses, and the efforts of U.S. Truce Commissioners T.M. Newell and Thomas Spalding on the Georgia coast to negotiate the return of slaves who had enlisted in, or sought asylum with, the British Corps of Colonial Marines still at Cumberland Island under the command of Rear Admiral George Cockburn. Cockburn was not inclined to voluntarily hand over British military personnel who risked being returned to slavery by the Americans. Cockburn also professed difficulty in communicating news of the Treaty of Ghent to Nicolls and his forces. There was a whiff of panic in St. Marys and Savannah at this time.

Nicolls contributed to diplomatic tensions between the United Kingdom and the United States in the Spanish Floridas over slavery related issues arising from Jackson's Treaty with the Creeks, the Treaty of Ghent, and Nicolls's attempts to represent the interests of the Native Americans and blacks who had taken up arms on the British side. Writing from HMS Royal Oak, off Mobile Bay, on 15 March 1815, Rear Admiral Pulteney Malcolm, Cochrane's subordinate commander of the Mobile Squadron, assured Don Mateo Gonzalez Manrique, the Governor at Pensacola, that Post - Captain Robert Cavendish Spencer of HMS Carron, (a son of George Spencer, 2nd Earl Spencer), had been detailed to conduct a strict inquiry into the conduct of Nicolls and Captain Woodbine, respecting the losses in property to Spanish inhabitants of the Floridas. Malcolm believed that in cases where former slaves could not be persuaded to return to their owners, the British government would undertake to remunerate the owners.

Prior to leaving British Post for Great Britain, Nicolls engaged in a heated exchange of letters with U.S. Indian Agent Benjamin Hawkins. Hawkins accused Nicolls of being overzealous and of overstepping his authority in his personal defense of Redstick Creeks, Seminoles, and their Marron Creole or Black Allies, who some Americans in authority viewed as nothing more than runaway slaves and lost or unclaimed property.

Nicolls left in the summer of 1815 with the Redstick Creek Prophet, Josiah Francis (or Hillis Hadjo, the Native American Indian spiritual and political leader known for his role in the Battle of Holy Ground), and an Anglo - Creek - Seminole treaty of Nicolls' own initiative. Nicolls, Woodbine, and a Redstick Creek leader, probably Josiah Francis, arrived at Amelia Island, in Spanish East Florida on 7 June 1815, where rumors circulated that the officers were seeking to either obtain British possession of the Floridas from Spain, or at least to arm and supply the Florida factions resisting American territorial expansion. In leaving West Florida, according to the U. S. Indian Agent Hawkins, Nicolls had left local forces with the arms and means to resist advancing American encroachments which were leading up to Andrew Jackson's First Seminole War.

In England, Nicolls failed to obtain official support for the Creeks, and Josiah Francis failed to receive official recognition for his credentials as the Redstick Creek emissary from the Foreign Office, although he did receive honorary recognition as a former Colonel of the British Army in Florida as well as publicized encounters with British notables, including the Prince Regent, before returning to Spanish West Florida aboard a British sloop of war in 1816. Nicolls himself, however, was retained on full pay status in the duties of a Captain of Royal Marines with the brevet rank of Major.

In the summer of 1817 Captain George Woodbine, one of Nicoll's former subordinate officers, was present in Spanish East Florida together with the former British soldier and Scottish mercenary lieutenant of Simon Bolivar, Gregor MacGregor. Woodbine and Macgregor both left Spanish East Florida to rejoin the Latin American revolutionary movement prior to U.S. military intervention in East Florida. The names of Nicolls, Woodbine and Macgregor, had become associated with the arming of blacks as soldiers, militiamen, and even as mercenaries. The threat, real or imaginary, was an anathema to North American popular conceptions of the time.

The Niles' Weekly Register of Baltimore also published, between July and October 1818, portions of correspondence between Nicolls and the former auxiliary 2nd Lt Robert Chrystie Armbrister (1797 – 1818) of the first battalion of the (2nd) British Corps of Colonial Marines. Armbrister was one of two British subjects executed in the Arbuthnot and Ambrister incident by order of Major General Andrew Jackson following a drumhead trial at Saint Marks in Spanish West Florida in April 1818. The Seminole, or Redstick Creek Prophet, Josiah Francis / Hillis Hadjo, the same Indian Chief who had accompanied Nicolls to England in 1815, and another Seminole leader, Nehemathla Micco, were also summarily executed by the Americans in Spanish territorial waters in April 1818. In the correspondence of Armbrister, assistance is asked of Nicolls to intervene with the British government on behalf of former allies seeking asylum in Spanish West Florida from perceived American wrongdoing and injustice.

In 1823, Nicolls became the first Royal Marines commandant of Ascension Island. Ascension is a small volcanic island in the South Atlantic, halfway between South America and Africa. In 1815, HMS Zenobia and HMS Peruvian took the island to prevent it from being used as a staging post from which to rescue Napoleon Bonaparte from Saint Helena. From 1815 until Nicolls took over, the Royal Navy registered the island as a "small Sloop of 50 or 60 Men", HMS Ascension, since the Navy was forbidden to govern colonies. The island had a garrison of about thirty, with a few families, servants, and liberated Africans. The Royal Navy came to use the island as a victualing station for ships, particularly those of the West Africa Squadron (or Preventative Squadron), which were working to suppress the slave trade.

Water was scarce, and an important task for Nicolls was to ensure that the island had a stable source of water. He achieved this by installing systems of pipes and carts to bring water to the settlement from the few springs in the mountains. Food was mostly shipped from England, but some could be procured locally: fish, a few vegetables grown on the island, feral goats and sheep, fishy tasting eggs from a tern colony on the island, and turtle meat obtained during the laying season from December to May. Due to Nicolls's efforts in directing the harvest of turtles, turtle meat, an expensive delicacy in England, became so common it was fed to prisoners and pigs, and Marines complained of it. This surfeit of turtle irritated Nicolls's superiors and the Lords of the Admiralty, and when an Admiral ordered Nicolls to stop feeding turtle to prisoners, he started selling or bartering it to visiting ships. With this monotonous diet, men on the island relied on rum for spice. Nicolls understood this, and gave large rations of grog when his men showed "spirited and Soldierlike feelings".

On the confines of the island feuds were vicious, and one surgeon went insane. Pirates were frequently seen off Ascension, keeping the garrison on edge. Nicolls was also busied by many infrastructure projects on the island, building roads, water tanks, a storehouse, and developing the gardens on Green Mountain. For these efforts, Nicolls had about sixty freed Africans sent to Ascension, and additionally asked for convicts.

Nicolls had many such grand schemes for trade between Britain and its colonies, but these all failed to materialize. These schemes included a plan to grow oaks in Sierra Leone for Royal Navy ships, a plan to ship Ascension rocks to England, and a plan to ship New Zealand flax to England which he discussed in a letter to Henry Bathurst, 3rd Earl Bathurst. On 3 November 1828 Captain William Bate replaced Nicolls as commandant on Ascension.

In 1829, Nicolls was appointed Superintendent of Fernando Po (now Bioko), a tropical island immediately off the coast of Africa, which the Navy used as a base for operations against the slave trade. Nicolls received the appointment after colonial administrator William Fitzwilliam Owen had refused the post, and after merchant John Beecroft was deemed unfit for the post. Owen, however, voiced his dissatisfaction with what he viewed as Nicolls's harsh rule on the island, and Beecroft increased his influence in the area. Nicolls, in turn, attacked Beecroft for his dealings with former slavers. Nicolls's health suffered in Fernando Po and by April 1830 he had left for Ascension. When Nicolls returned to England ill, Beecroft was placed in charge of the island. Tropical illness took a toll on the Europeans at Fernando Po, where hundreds died during the period. Nineteen of the 34 men in Nicoll's first contingent died soon after their arrival, and only five of the original 47 Royal Marines who accompanied him to Fernando Po in 1829 survived two years duty on the station. Lieutenant Colonel Edward Nicolls, somewhat restored to health, served a second term as Superintendent of Fernando Po during 1832 – 1833. Despite his differences with Owen, Nicolls was just as determined to disrupt the slave trade, and equally energetic in his attempts to convince the British government to adopt a more aggressive stance. Frustrated in territorial annexation schemes, he invited the West African rulers of Bimbia, Old Calabar, Camaroon, Malimba, and the Bonny to Fernando Po to form an anti - slavery alliance. To Nicolls' great disappointment, the British government ordered him to evacuate Fernando Po on 29 August 1832, and put an end to operations there. Unfinished work and efforts to provide for the welfare of liberated and displaced slave populations delayed the end of Nicoll's mandate for several months, and the Colonel did not return to England until April 1835.

During his time in control of Fernando Po, Nicolls clashed with the Portuguese authorities on the neighboring islands of São Tomé and Príncipe regarding his refusal to return slaves escaping from there. In a 1842 letter to The Times he says he was accused by the Portuguese governor, Senhor Ferreira, of deliberately enticing slaves to run away and of encouraging 'thieves' and 'murderers'. This charge he denied, asserting that he had never actively encouraged slaves from nearby islands to make the dangerous crossing to Fernando Po: but that if they chose to do so, it was his duty under British law not to return them to slavery. He considered those slaves who killed in the course of their escapes as legally and morally justified in their action; nor did he regard them as thieves for having seized canoes to escape in. He offered to return the canoes however, and informed Ferreira that if the latter could persuade any of the escapees to return voluntarily to a state of slavery, Nicolls would not impede them. He wrote to The Times on the subject because of the debate which followed the Creole case in which slaves transported aboard an American vessel had taken control of her and forced the crew to take them to a British run port.

As a retired Major of Marines, Nicolls was promoted to the honorary (British Army Brevet) rank of General in 1855, just months after his Army Brevet promotion to Lieutenant General. In July 1855 he was made Knight Commander of the Bath (KCB).

In 1809, while still a young Captain of Marines, Nicolls married Miss Eleanor Bristow (1792 – 1880) who was also from northern Ireland. Sir Edward and Lady Eleanor Nicolls appear on the United Kingdom Census 1861 in Greenwich, where Nicolls is listed as KCB and a retired General of Marines.

The General and Lady Nicolls had the following children: Alicia Nicolls (born in 1810); Eleanor Hestor Nicolls (1811 – 1898, born at Woolwich, later married Macgregor Laird); Edwina Anna Nicolls (1814 – 1902); Jane Mary Nicolls (1819 – 1901), who married Captain Archibald Douglas William Fletcher RN (1821 – 1882); Elizabeth Nicolls (1821 – 1856); Lieutenant Edward Nicolls RN (1821 – 1844) who died while serving as first lieutenant of HMS Dwarf; and Major Richard Orpin Townsend Nicolls (1823 – 1862) of the Madras Staff Corps (Indian Army). Edwina Anna married John Hill Williams on 22 June 1853. General Nicoll's daughter Elizabeth married the educator John Richard Blakiston (1829 – 1917) on 6 June 1854, dying in February 1856 without issue.

Nicolls died at his residence in Blackheath, London on 5 February 1865. His widow, Lady Eleanor Nicolls, survived her husband 15 years. Having suffered an injury in an accident at home on 14 November 1880, she died ten days later at the age of 88.

On December 24, 1814, the members of the British and American negotiating teams signed and affixed their individual seals to the document, which once ratified by their respective governments, ended the war of 1812. The treaty released all prisoners and restored all war lands and boats, resulting in several changes. Returned to the United States were approximately 10,000,000 acres (40,000 km²) of territory, near Lakes Superior and Michigan, in Maine and on the Pacific coast. American held areas of Upper Canada (present day Ontario) were returned to British control. The treaty made no major changes to the pre-war situation, but Britain promised to return the freed black slaves encouraged during the war to escape to British territory. In practice, a few years later Britain instead paid the United States $1,204,960 for them.

The British proposal to create an Indian buffer zone in Ohio and Michigan collapsed after the Indian coalition fell apart.

News of the treaty finally reached the United States after the American victory in the Battle of New Orleans and the British victory in the Second Battle of Fort Bowyer, but before the British assault on Mobile, Alabama. Skirmishes occurred between U.S. troops and British allied Indians along the Mississippi River frontier for months after the treaty, including the Battle of the Sink Hole in May 1815.

The U.S. Senate unanimously approved the treaty on 16 February 1815, and President James Madison exchanged ratification papers with a British diplomat in Washington on 17 February; the treaty was proclaimed on 18 February. Eleven days later, on 1 March Napoleon escaped from Elba, starting the war in Europe again, and forcing the British to concentrate on the threat he posed.

In 1922, the Fountain of Time was dedicated to the city of Chicago, being placed in Washington Park marking 100 years of peace between the United States and the United Kingdom. The Peace Bridge between Buffalo, New York, and Fort Erie, Ontario, opened in 1927, commemorates 100 years of peace between the United States and Canada.