[2] Lord Stirling commanded a brigade at the Battle of Long Island, his rearguard action resulting in his capture but enabling General George Washington's troops to escape.
He was educated, ambitious, and proficient in mathematics and astronomy, he then joined his mother, Mary Alexander, the widow of David Provost, in the provision business left her by the death of her first husband.
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.
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.
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.
[6] He inherited a large fortune from his father, dabbled in mining and agriculture, and lived a life filled with the trappings befitting a Scottish lord.
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.
He held against repeated attacks by a superior British Army force under the command of Gen. James Grant at the Old Stone House near Gowanus Creek and took heavy casualties.
Stirling himself was taken prisoner but he had held the British forces occupied long enough to allow the main body of Washington's army 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, Washington was able to barge his remaining troops and equipment across back to Manhattan and New York City.
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.
Washington held him in such high regard that during the second Middlebrook encampment, he placed him, headquartered at the nearby Van Horne House, in command of the Continental Army for nearly two months, from December 21, 1778, when he left to meet with Congress in Philadelphia, until he returned about February 5, 1779.
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.
[citation needed] 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.
His love of the bottle was notorious..." One of Gates' aides, James Wilkinson, stopped at Stirling's headquarters at Reading, Pennsylvania and stayed for dinner because it was raining.
Finally, he claimed to have read a letter from Thomas Conway to Gates that stated, "Heaven has determined to save your country or a weak general and bad counselors would have ruined it".
A memorial tablet to the Alexander family can be found in the Churchyard of Trinity Church, facing the historic Wall Street district (adjoining nearby St. Paul's Chapel), in New York City.