Stephen Van Rensselaer III (/ˈrɛnslər, -slɪər/;[4] November 1, 1764 – January 26, 1839) was an American landowner, businessman, militia officer, and politician.

After the demise of the Federalist Party, Van Rensselaer was a John Quincy Adams supporter and served in the United States House of Representatives for one partial term and three full ones.

Long active in the militia, Van Rensselaer attained the rank of major general; he commanded troops on the New York–Canada border during the War of 1812, but resigned his commission after defeat at the Battle of Queenston Heights.

After Van Rensselaer's 1839 death, efforts by his sons to collect past due lease payments led to the Anti-Rent War, and the break up and sale of the manor.

As the heir to and then owner of one of the largest estates in New York, Van Rensselaer's holdings made him the tenth richest American of all time, based on the ratio of his fortune to contemporary GDP.

His family was very wealthy, and the Van Rensselaer Manor House was a rich childhood environment for the young boy to grow up in.

[8][9] On his 21st birthday, Van Rensselaer took possession of Rensselaerswyck, his family's 1,200 square mile (3,072 km2) estate, and began a long tenure as lord of the manor.

[11] Instead, he developed the land by granting perpetual leases at moderate rates; Van Rensselaer derived a steady rental income from his property, while tenants were able to become successful farmers without having to pay a large purchase price up front.

Van Rensselaer, over his time in politics, acquired a reputation as something of a reformer, voting in favor of extending suffrage and going against much of New York's upper class in doing so.

In 1801, Van Rensselaer presided over the state constitutional convention,[23] was the Federalist nominee for Governor of New York, and lost to George Clinton, 24,808 votes to 20,843.

[24] He was one of the first to advocate for a canal from the Hudson River to the Great Lakes and was appointed to a commission to investigate the route in 1810,[25] reporting favorably to the Assembly in 1811.

Because none of the four candidates received a majority of electoral votes in the 1824 presidential election, the U.S. House had to choose from the top three finishers—Adams, Andrew Jackson, and William H. Crawford.

When war was declared on Great Britain in June 1812, Van Rensselaer was a leading Federalist candidate for Governor of New York.

Democratic-Republican Party leaders, including President James Madison and incumbent New York Governor Daniel D. Tompkins, devised a way to remove Van Rensselaer from the campaign by offering him command of the Army of the Centre—U.S.

If Van Rensselaer declined a military leadership role during a time of war, he would lose esteem in the eyes of the voters.

But the Army of the Centre consisted largely of untrained, inexperienced militiamen; under the Constitution, which stressed that the role of the militia was to enforce laws, prevent insurrection, and repel invasion, they did not have to cross into Canada to fight.

The British were in the process of fortifying the Queenston Heights that Van Rensselaer would have to attack, and his officers were itching for action despite their general's desire to delay until his troops were better trained and organized.

Though initially successful, Van Rensselaer's inadequate preparations and his plan of attack were clearly main reasons for what became a major defeat.

Despite significantly outnumbering the British in the early stages of the battle, the American soldiers, untried and untrained, sometimes refused to cross to the Canadian side of the river.

Once the tide of the battle turned, Van Rensselaer was not even able to coax the boatmen into going back over to rescue the doomed attack force.

The defeat at Queenston Heights spelled the end to Van Rensselaer's active military career; after the battle, he resigned his post.

[22] He led the parade of militia members, fire fighters, Revolutionary War veterans and others, which culminated in speeches and a eulogy by William Buell Sprague.

[56] His granddaughter, Justine Van Rensselaer (1828–1912), married Dr. Howard Townsend, a noted physician at Albany Medical College.

[57] His grandson, Stephen Van Rensselaer Cruger married Julia Grinnell Storrow, a popular American novelist.