Nearly half a century later, after the United States Army had built Fort Laramie without permission on Lakota land, the Fort Laramie Treaty of 1851 was negotiated to protect travelers on the Oregon Trail.

In 1851 United States Army post Fort Chadbourne was established to protect the frontier, and the fort was manned until the Civil War.

Supported by Brazil and the Uruguayan liberals, he created the " Big Army " and forced Manuel Oribe to capitulate, ending the long siege of Montevideo in October 1851, and finally defeating Rosas on 3 February 1852 at the Battle of Caseros.

Daguerreotypist John Wesley Jones visited the garrison in 1851 and Samuel C. Mills, traveling with the Army bound for Utah, produced at least one image of Fort Bridger in 1858.

James Miller ( April 25, 1776 – July 7, 1851 ) was a member of the United States House of Representatives from New Hampshire, the first Governor of Arkansas Territory, and a Brigadier General in the United States Army during the War of 1812.

Between the wars he served in the U. S. Army Adjutant General's office and as an adjutant in California, reaching the rank of captain in 1851.

Major Walter Reed, M. D., ( September 13, 1851 – November 22, 1902 ) was a U. S. Army physician who in 1900 led the team that postulated and confirmed the theory that yellow fever is transmitted by a particular mosquito species, rather than by direct contact.

In 1851 the U. S. Army Corps of Engineers began to clear obstacles from the strait with explosives ; the process would last seventy years.

George Augustus Frederick Brooke, younger son of the first Baronet, was the father of 1 ) Arthur Thomas Brooke ( d. 1893 ), a Captain in the Royal Navy, 2 ) Henry Francis Brooke ( 1836 – 1880 ), a Brigadier-General in the British Army, 3 ) Lionel Godolphin Brooke ( 1849 – 1931 ), a Brigadier-General in the Connaught Rangers, and 4 ) Frank Brooke ( 1851 – 1920 ), a businessman and public servant.

General Sir Roger Hale Sheaffe, 1st Baronet ( 15 July 1763 – 17 July 1851 ) was an American-born General in the British Army in the first part of the 19th century.

* Eidgenössischer Stutzer 1851, a historical service rifle of the Swiss Army

The first Army national old soldiers ' home in the U. S. was established in Washington, D. C. in 1851.

In 1851, part of the Sydney Common south of Victoria Barracks was granted to the British Army for use as a garden and cricket ground for the soldiers.

Roberts was educated at Eton, Sandhurst and Addiscombe Military Academy before entering the East India Company Army as a Second Lieutenant with the Bengal Artillery on 12 December 1851.

The earliest true mitrailleuse was invented in 1851 by Belgian Army Captain Fafschamps, 10 years before the advent of the Gatling gun.

The first " mitrailleuse " was a manually fired 50-barrel volley gun originally developed in Belgium in 1851, 10 years before the advent of the Gatling gun, by the Belgian Army Captain Fafschamps, who made a rough prototype and drawings of his invention.

With the exception of Western influenced units such as the " Ever-Triumphant Army " of the Taiping Rebellion ( 1851 – 66 ) Chinese armies of the 19th century wore dress that was broadly variegated.

Vallejo gave the Rancho Suscol to his oldest daughter, Epifania Guadalupe Vallejo, April 3, 1851, as a wedding present, when she married U. S. Army General John H. Frisbie.

In 1851, she moved to California from West Point with her parents, Charles, an Army doctor, and Martha Hitchcock.

When the U. S. Army built Fort Union in the Mora Valley in 1851, the soldiers were unaware that they had encroached on private property, which was part of the Mora Grant.

The use of colors to distinguish branches of the United States Army dates to 1851.

He joined the U. S. Army as an assistant surgeon in 1851 and served in that capacity for ten years.

In November 1851, during the administration of Supreme Director Laureano Pineda, he became Commander-in-chief of the Army.

The son of a colonel in the Army, he was educated at Cheltenham College, and in 1851 was commissioned in The Carabiniers ( 6th Dragoon Guards ).

* March 18 – William Elbridge Sewell, American naval officer and Governor of Guam ( b. 1851 )

When the new settlement was gazetted in 1851 it was named ' Sale ' — a tribute to General Sir Robert Sale, a British army officer who won fame in the first Afghan war before being killed in battle in India in 1845.

In 1851, he returned to West Point as a cavalry and artillery instructor, where he established a close professional and personal relationship with another Virginia officer, Lt. Col. Robert E. Lee, the Academy superintendent.

The elder Frederick, a Danish military officer, had been one ( and perhaps the foremost ) of the candidates of Christian VIII of Denmark in the 1840s to succeed to the Danish throne if the latter's male line died out, but renounced his rights to the throne in 1851 in favor of his sister, Louise.

* William Johnson ( Royal Navy officer ) ( 1784 – 1851 ), Scottish Naval Captain

* John Piper ( military officer ) ( 1773 – 1851 ), lieutenant-governor of Norfolk Island

In 1826 François Pouqueville, French diplomat and archaeologist, who wrote the Voyage en Grèce ; in 1851 Ernst Curtius the German archaeologist and historian who speculated about its location ; in 1879 Julius Smith, the director of Athens Observatory, issuing a study comparing the Aegeion earthquake which occurred 26 December 1861 with an earthquake which might have destroyed Helike ; in 1883 Spiros Panagiotopoulos, the mayor of Aegeion city, wrote about the ancient city ; in 1912 the Greek writer P. K. Ksinopoulos wrote The City of Aegeion Through the Centuries, and in 1939 Stanley Casson, an English art scholar and army officer who studied classical archaeology and served in Greece as liaison officer, addressed the problem.

Rear Admiral Aaron Ward ( October 10, 1851 – July 5, 1918 ) was an officer in the United States Navy during the Spanish-American War.

He was an officer in the steamer Princeton during the Mexican-American War and executive officer of the frigate St. Lawrence in 1851.

On November 3, 1851, the first Irish born Boston Police officer, Bernard " Barney " McGinniskin, was appointed.

* Henry Heathcote ( 1777 – 1851 ), Royal Navy officer

Lewis Warrington ( 3 November 1782 – 12 October 1851 ) was an officer in the United States Navy during the Barbary Wars and the War of 1812.

Commodore Alexander Scammel Wadsworth ( 1790 – April 5, 1851 ) was an officer of the United States Navy.

In 1851 the 4th ( Hazara ) Mountain Battery was raised at Haripur from Hazara gunners, who were trained by Major Abbott, a British officer and first deputy commissioner of Hazara, in order to defend the district.

* Lord John Hay ( politician ) ( 1788 – 1851 ), British Royal Navy officer and Whig politician

Frederick Courteney Selous DSO (; 31 December 1851 – 4 January 1917 ) was a British explorer, officer, hunter, and conservationist, famous for his exploits in South-East Africa.

Anton Haus ( June 13, 1851 – February 8, 1917 ) was an Austrian naval officer.

Kane was appointed senior medical officer of the Grinnell Arctic expedition of 1850 – 1851 under the command of Edwin de Haven, which searched unsuccessfully for the lost expedition of Sir John Franklin.

John Piper ( 20 April 1773 – 8 June 1851 ) was a military officer, public servant and landowner in the colony of New South Wales.

Balch then served as executive officer of the sloop-of-war, sailing to the Orient on 23 August 1851 for an extended cruise on the East Indies Station.