Lord Stirling commanded the 1st Maryland Regiment that fought at the Battle of Long Island. He lost the battle and was captured but his actions allowed General George Washington's troops to escape. Stirling was returned by prisoner exchange, promoted for his actions, and served with distinction throughout the war. He was trusted by Washington and in 1778 he exposed the Conway Cabal.
Alexander was educated, ambitious, and proficient in mathematics and astronomy. He joined his mother, Mary Alexander, in a successful business and, in 1747, married Sarah Livingston, the daughter of Philip Livingston (1686-1749) and sister of Governor William Livingston. The couple had two daughters and one son William. One of his daughters, Mary Alexander, would marry a wealthy merchant named Robert Watts of New York. Another daughter Catherine was the wife of Congressman William Duer.
The title Earl of Stirling became dormant or extinct upon the death of Henry Alexander, 5th Earl of Stirling. William's father, James Alexander, who had fled from Scotland in 1716 after participating in the Jacobite rising, did not seek the title. Upon his father's death, William lay claim to the title and filed suit. His relationship to the 5th Earl was not through heirs of the body, but through heir male collateral, thus, he was not entitled to a title inherited only by the male line descendants of the first earl. However, the inheritance by proximity of blood had been questioned. It was settled in his favor, by a unanimous vote of a jury of twelve in a Scottish court in 1759, and William claimed the disputed title of Earl of Stirling. It is not clear if the case went to court because of an unfavorable answer from the Lord Lyon King of Arms concerning the peerage.
Legal opinion was that this was a "Scottish heir" problem so the title right was solved. This might have been unopposed, as indisputable peerage, except there was a catch. The two sponsors, Archibald Campbell, 3rd Duke of Argyll, and John Stuart, 3rd Earl of Bute, encouraged William Alexander through representatives to seek the title. The goal was vast land holdings in America that the holder of the title was to enjoy. The sponsors were to receive money and land if William was successful. With this in mind, William decided to petition the House of Lords. A friend and professional agent in Scotland, Andrew Stuart, wrote and advised William not to petition the House of Lords. He felt that the right of indisputable peerage demanded that William just claim the titles as others had done. His opinion was that others lay similar claims to titles so he would not be opposed. It is possible William did not want to commit a crime, or be found out, and if the House of Lords advanced his claim it would be forever legal. One problem was that to prove his claim in court, two old men were called upon to testify that William did in fact descend from the first Earl through his uncle named John Alexander. This might have been persuasive in a Scottish court but might be considered dubious in England.
Alexander inherited a large fortune from his father. He dabbled in mining and agriculture and lived a life filled with the trappings befitting a Scottish Lord. This was an expensive lifestyle and he eventually went into debt to finance it. He began building his grand estate in the Basking Ridge section of Bernards Township, New Jersey and upon its completion, sold his home in New York and moved there. George Washington was a guest there on several occasions during the revolution and gave away Alexander's daughter at her wedding. In 1767, the Royal Society of Arts awarded Alexander a gold medal for accepting the society's challenge to establish viticulture and wine making in the North American colonies by cultivating 2,100 grape (V. vinifera) vines on his New Jersey estate.
When the American Revolutionary War began, Stirling was made a colonel in the New Jersey colonial militia. Because he was wealthy, he outfitted the militia at his own expense and was willing to spend his own money in support of the Patriot cause. He distinguished himself early by leading a group of volunteers in the capture of an armed British naval transport.
The Second Continental Congress appointed him brigadier general in the Continental Army in March 1776.
At the Battle of Long Island, in August of that year, Stirling led the stalwart, well-trained 1st Maryland Regiment (also known as the "Maryland Line") in repeated attacks against a superior British Army force under command of Gen. William Howe at the Old Stone House near Gowanus Creek and took heavy casualties. The redcoats had made a wide flanking attack sweeping to the east through the lightly-guarded Jamaica Pass, one of a series of low entrances through the ridge line of hills running east to west through the center of Long Island, catching the Patriot forces on their left side. Outnumbered twenty-five to one, his brigade was eventually overwhelmed and Stirling himself was taken prisoner during the disciplined and measured retreat, but not before repelling the British forces long enough to allow the main body of Washington's Continental troops to escape to defensive positions at Brooklyn Heights, along the East River shoreline. Later, under the cover of a miraculous fog which enveloped the river, and the rear-guard covering actions of the Marylanders, Washington was able to barge his remaining troops and equipment across back to Manhattan Island and New York Town. Because of his actions at Long Island, one newspaper called Stirling "the bravest man in America", and he was praised by both Washington and the British for his bravery and audacity. Later a commemorative monument was erected at the site of the military engagements and embattled retreat and the plot of land deeded to the State of Maryland near Prospect Park as a sacred parcel of "blood-soaked Maryland soil".
Stirling was released in a prisoner exchange, in return for governor Montfort Browne, and promoted to the rank of major general, and became one of Washington’s most able and trusted generals. Washington held him in such high regard that he placed Stirling in command of the entire Continental Army for nearly two months while he was away on personal business, and throughout most of the war he was considered to be third or fourth in rank behind General Washington. At the Battle of Trenton on 26 December 1776, he received the surrender of a Hessian German mercenary regiment. On 26 June 1777, at Matouchin, he awaited an attack, contrary to Washington's orders. His position was turned and his division defeated, losing two guns and a hundred fifty men in the Battle of Short Hills. Subsequent battles at Brandywine and Germantown in Pennsylvania during the campaign to defend the Patriot capital of Philadelphia and Monmouth in New Jersey, cemented his reputation for bravery and sound tactical judgment. At the battles of Brandywine and Germantown he acted with bravery and discretion. At Monmouth, he displayed tactical judgment in posting his batteries, and repelled with heavy loss an attempt to turn his flank. During the devastating winter encampment at Valley Forge, northwest of British–held Philadelphia, his military headquarters have been preserved. In January 1780, he led an ineffective raid against Staten Island on the western shores of New York Bay. Lord Stirling also played a part in exposing the Conway Cabal, a conspiracy of disaffected Continental officers looking to remove Washington as Commander-in Chief and replace him with General Horatio Gates.
When Washington and the French comte de Rochambeau took their conjoined armies south for the climactic Battle of Yorktown in 1781, Stirling was appointed commander of the elements of the Northern Army left behind to guard New York and was sent up the Hudson River to Albany.
Always a heavy drinker, he was in poor health by this time, suffering from severe gout and rheumatism. He died in Albany on the 15th January 1783. His death, just months before the official end of the American War of Independence with the Treaty of Paris of 1783, is the probable reason that he is not as well known today as many other Revolutionary War generals. Still, his significant contributions made him one of the most important figures of the American Revolution. He was buried in the Churchyard of Trinity Church, facing the historic Wall Street district (adjoining nearby St. Paul's Chapel), in New York City.His nephew was Senator John Rutherfurd (1760–1840).
His son-in-law was Congressman William Duer (1747–1799).
His grandson was College president William Alexander Duer (1780–1858).
His great-grandson was Congressman William Duer (1805–1879).
His great-grandson was General Stephen Watts Kearny (1794–1848)
His great-great-grandson was General Philip Kearny, Jr. (1815–1862) who died in action during the Civil War
MS51, a Middle School on the former Gowanus battlefield, is named William Alexander Middle School.
Stirling, New Jersey, an unincorporated community in Long Hill Township is located a short distance from Alexander's house in Basking Ridge.
The Lord Stirling School in New Brunswick, New Jersey is named for him.
Lord Stirling Park in Basking Ridge, New Jersey is located on part of his estate.
Sterling Hill Mine was named after him, as he once owned the property
Lord Stirling 1770s Festival
The town of Sterling, Massachusetts.