Armstrong was born in Carlisle, Pennsylvania, the younger son of General John Armstrong and Rebecca Armstrong. John Armstrong Sr. was a renowned Pennsylvania soldier born in Ireland of Scottish descent. John Jr.'s older brother was James Armstrong, who became a physician and U.S. Congressman. After early education in Carlisle, John Jr. studied at the College of New Jersey. He broke off his studies in Princeton in 1775 to return to Pennsylvania and join the fight in the Revolutionary War.
Career
Revolutionary War
The young Armstrong initially joined a Pennsylvania militia regiment and the following year he was appointed as aide-de-camp to General Hugh Mercer of the Continental Army. In this role, he carried the wounded and dying General Mercer from the field at the Battle of Princeton. After the general died on January 12, 1777, Armstrong became an aide to General Horatio Gates. He stayed with Gates through the Battle of Saratoga then resigned due to problems with his health. In 1782 Gates asked him to return. Armstrong joined General Gates' staff as an aide with the rank of major, which he held through the rest of the war.
Newburgh letters
While in camp with Gates at Newburgh, New York, Armstrong became involved in the Newburgh Conspiracy. He is generally acknowledged as the author of the two anonymous letters directed at the officers in the camp. The first, titled "An Address to the Officers", called for a meeting to discuss back pay and other grievances with the Congress and form a plan of action. After George Washington ordered the meeting canceled and called for a milder meeting on March 15, a second address appeared that claimed that this showed that Washington supported their actions. Washington successfully defused this protest without a mutiny. While some of Armstrong's later correspondence acknowledged his role, there was never any official action that connected him with the anonymous letters.
After the revolution
Later in 1783 Armstrong returned home to Carlisle and became an Original Member of the Pennsylvania Society of the Cincinnati. He was named the Adjutant General of Pennsylvania's militia and also served as Secretary of the Commonwealth of Pennsylvania under Presidents Dickinson and Franklin. In 1784, he led a military force of four hundred militiamen into a controversy with Connecticut settlers in the Wyoming Valley of Pennsylvania. His tactics enraged the nearby states of Vermont and Connecticut, which sent their own militia into the area. Timothy Pickering was dispatched to forge a solution to the difficulty, and the settlers were able to keep title to the land they had tamed. In 1787 and 1788 Armstrong was sent as a delegate for Pennsylvania to the Congress of the Confederation. The Congress offered to make him chief justice of the Northwest Territory. He declined this, as well as all other public offices for the next dozen years. Armstrong resumed public life after the resignation of John Laurance as U.S. Senator from New York. As a Jeffersonian Republican he was elected in November 1800 to a term ending in March 1801. He took his seat on November 6, and was re-elected on January 27 for a full term, but resigned on February 5, 1802. DeWitt Clinton was elected to fill the vacancy, but resigned in 1803, and Armstrong was appointed temporarily to his old seat. In February 1804, Armstrong was elected again to the U.S. Senate to fill the vacancy caused by the resignation of Theodorus Bailey, thus moving from the Class 3 to the Class 1 seat on February 25, but served only four months before President Jefferson appointed him U.S. Minister to France. He served in that post until 1810, and also represented the United States at the court of Spain in 1806. When the War of 1812 broke out, Armstrong was called to military service. He was commissioned as a Brigadier General, and placed in charge of the defenses for the port of New York. Then in 1813 President Madison named him Secretary of War. Henry Adams wrote of him:
In spite of Armstrong's services, abilities, and experience, something in his character always created distrust. He had every advantage of education, social and political connection, ability and self-confidence; he was only fifty-four years old, which was also the age of Monroe; but he suffered from the reputation of and. So strong was the prejudice against him that he obtained only eighteen votes against fifteen in the Senate on his confirmation; and while the two senators from Virginia did not vote at all, the two from Kentucky voted in the negative. Under such circumstances, nothing but military success of the first order could secure a fair field for Monroe's rival.
Armstrong made a number of valuable changes to the armed forces but was so convinced that the British would 'not' attack Washington D.C. that he did nothing to defend the city even when it became clear it was the objective of the invasion force. After the destruction of Washington, Madison, usually a forgiving man, forced him to resign in September 1814.
Later life
Armstrong returned to his farm and resumed a quiet life. He published a number of histories, biographies, and some works on agriculture. He died at La Bergerie, the farm estate he built in Red Hook, New York in 1843 and is buried in the cemetery in Rhinebeck. Following the death of Paine Wingate in 1838, he became the last surviving delegate to the Continental Congress, and the only one to be photographed.
Personal life
In 1789, Armstrong married Alida Livingston, the youngest child of Judge Robert Livingston and Margaret Livingston. Alida was also the sister of Chancellor Robert R. Livingston and Edward Livingston. Together they had seven children:
William Armstrong, who married Lucy A. Hickernell.
Armstrong died in Red Hook, New York on April 1, 1843. He was buried at the Rhinebeck Cemetery in Rhinebeck, New York.
Residences
Almont
Armstrong's initial farm in Dutchess County, called "Altmont", was originally part of the Schuyler patent. In 1795, he purchased a part of the farm from the Van Benthuysen family, and converted an existing barn into a two-story Federal style dwelling with twelve rooms. Around 1800, Armstrong sold "Almont" to Andrew and Anna Verplanck Deveaux. Deveaux died in 1812; in 1816 his widow sold "Deveaux Park" to John Stevens. The mansion burned down around 1879. In 1908, lumber rights to the white oak and chestnut forests were sold for timber for the New York market.
La Bergerie
After the death of Margaret Beekman Livingston, widow of Judge Robert Livingston, much of the Clermont land was distributed among the heirs. John R. Livingston received the land that would become the "Messena" estate. His sister Alida Livingston Armstrong inherited the property just to the south. There the Armstrong's created "La Bergerie", an estate where they raised Merino sheep. The Astors purchased it for a summer home and renamed it Rokeby. Margaret Chanler Aldrich, great-granddaughter of Margaret Armstrong Astor, married Richard Aldrich. Rokeby remains in the Aldrich family.
