His ancestors were of Norman descent and first emerged when they joined the armies of William the Conqueror to invade England in 1066. John Crozier came to Ireland as a Cavalary Officer in 1630 with Lord Strafford, prior to that he came from Redworth Hall, County Durham and his family had been there since 1407.Before that time they were in Westmoreland which was then part of Yorkshire. Robert Crozier in 1262 obtained a grant of land from the Abbot of St Bees in Cumberland. In the family Arms which is used to this day are four bees and a cross indicating where they obtained their first grant.
The family consisted of Sir William (Was Household Steward to John O Gaunt )and Sir John Crozier who had many manors in the home counties near to London and lived at Stoke D'Abernon in Surrey. Also in the Family was William Crozier in the 1400s who was Canon of Glasgow, Arch Deacon of Teviotdale and he held many prebends, was a Papal Legate, one of the founding fathers of St Andrews University and was a Professor of Logic, he is well recorded in history and was connected to The Dougla's.
On his death he bequeathed to Philadelphia Museum ' The Crozier Collection ' which is a valuable collection of Antique Crystal, Porcelian and China. This prized Collection is today available for public viewing in Philadelphia.
On the death of his wife Mary Williams Crozier she left a considerable sum to Westpoint Academy for the purposes of the erection of a Hall which was built and is called Crozier Hall as a fitting memorial to Major General William Crozier.
Mary Williams Crozier left a very considerable balance of her estate in her will to The Connecticut College, New London which is remembered in the form of College Center at Crozier-Williams. It is affectionatly known today as The Cro, also a part of the building known as 'Crows Nest'. Already at Connecticut College is The Williams School which represents the Williams Family long connection with New London.
From 1879 to 1884 he was instructor in mathematics at West Point, and was superintendent of the Watertown, Massachusetts Arsenal from 1884 to 1887. In 1888 he was sent by the war department to study recent developments in artillery in Europe, and upon his return he was placed in full charge of the construction of gun carriages for the army, and with General Adelbert R. Buffington, the chief of ordnance, he invented the Buffington-Crozier disappearing gun carriage (1893). He also invented a wire-wound gun, and perfected many appliances connected with heavy and field ordnance.
In 1890 he attained the rank of captain. During the Spanish-American War he was inspector-general for the Atlantic and Gulf coast defences. In 1899 he was one of the American delegates to the Peace Conference at the Hague. He later served in the Philippine Islands on the staffs of Generals John C. Bates and Theodore Schwan, and in 1900 was chief of ordnance on the staff of General Adna Chaffee during the China Relief Expedition.
In November 1901 he was appointed brigadier-general and succeeded General Buffington as Chief of Ordnance of the United States Army. He served until 1918, not counting the time he was away at the Army War College in 1912 to 1913. He presided over adoption of such firearms as the famous M1911 to the obscure M1909 Benet-Mercie light machine gun, as well as the end/removal of the last of the 30-06 Gatling Guns from the Army arsenal. In addition, he also oversaw and authorized the various arsenals around the country to donate and sell various condemened cannon for use in town centers, soldier's monuments, and posts for fraternal organizations such as the Grand Army of the Republic. Many of these donated cannon can be seen in these locations to this day. His Notes on the Construction of Ordnance, published by the war department, were used as text-books in the schools for officers, and he also authored several other important publications on military subjects.
Other very famous firearm systems he presided over the adoption of include the M1903 rifle, the M1918 BAR (adopted in 1917), and the M1917 machine gun, all of which would serve well into the latter half of the 20th century. He also played a role in the rejection of the Lewis Gun by the Army, though it was used by the U.S. Marine Corps, and eventually, by the Army to a limited degree.
He died at age 87 in 1942.