This Irish couple built Ohio’s grandest frontier mansion—then Burr turned it into treason headquarters

The Blennerhassetts’ Downfall Through Burr’s Western Conspiracy

In 1798, Irish nobles Harman and Margaret Blennerhassett fled scandal to build a new life on an Ohio River island. They spent half their wealth on an 8,200-square-foot mansion that soon dazzled the frontier.

Life was good until 1805, when former Vice President Aaron Burr showed up with big plans. He talked Harman into funding what turned out to be a plot to split the west from America.

President Jefferson sent militia to raid the island in December 1806. The couple lost everything and died poor, though Burr walked free.

Today, Blennerhassett Island State Park keeps their wild tale alive for all who visit its rebuilt mansion.

Scandal Forced the Blennerhassetts to Flee Ireland

Harman Blennerhassett joined the secret Society of United Irishmen in the early 1790s to fight English rule in Ireland. When his father died in 1792, Harman got a huge $100,000 inheritance.

He shocked everyone in 1794 by marrying his niece Margaret Agnew. Their family saw this as incest and created a huge scandal.

The couple sold their Irish homes in 1795 to escape both political trouble and family members who couldn’t stand their relationship.

Their Ohio River Mansion Put the Wilderness to Shame

The couple landed in New York in 1796 and traveled to the Ohio River valley through Pittsburgh. They bought 174 acres on an island near today’s Parkersburg in 1798, land once owned by George Washington himself.

Between 1798 and 1800, they built a massive 8,200-square-foot mansion that ate up half of Harman’s money. With its fancy gardens, furniture, and party spaces, people soon called it “the West’s most beautiful home.

Frontier Life Looked Different for the Island Aristocrats

Margaret hosted important guests with French poetry, Shakespeare plays, and fancy parties with music and dancing. The couple ran a hemp farm using slaves and welcomed the top people in frontier society.

Harman spent his days doing science experiments, building his huge library, and running farm operations. People nicknamed the island “Eden” because it stood out so much from the rough wilderness around it.

A Disgraced Vice President Knocked on Their Door

Aaron Burr showed up at the island in May 1805, still on the run after killing Alexander Hamilton in their duel. The former Vice President was busy finding rich backers for a secret plan targeting southwestern lands.

Harman fell for Burr’s charm and grand talk of creating a new western nation separate from the United States. Margaret fully backed her husband, thinking he would get an important job in this new country Burr promised.

The Island Became Conspiracy Central

Harman spent his remaining fortune (about $37,500) on boats, supplies, and weapons for Burr’s plan. The island turned into the main base for the plot, with contracts signed for fifteen boats big enough to carry 500 men.

Harman even wrote essays called “The Querist” that talked about splitting up the United States. Burr sent a coded letter to General Wilkinson saying, “I have actually started the enterprise.

” The plan moved forward with the Blennerhassetts all in.

Jefferson Caught Wind of the Secret Plot

President Thomas Jefferson learned about the conspiracy in November 1806 when General Wilkinson betrayed Burr with warning letters. Jefferson acted fast, ordering everyone involved arrested on December 10.

The government called up Ohio and Virginia militias to stop all boat traffic and take over Blennerhassett Island.

Harman barely escaped downriver just hours before militia troops swarmed the island on December 10-11, 1806.

Soldiers Trashed Their Dream Home in One Night

Virginia militia tore through the mansion while Margaret visited friends in Marietta. She came home to find soldiers breaking furniture, stealing valuables, and drinking their wine.

Scared for her safety, Margaret grabbed her three children and ran into the night as militia kept occupying their home.

Meanwhile, Harman met Burr downriver, only to find their “army” had fewer than 100 men instead of thousands. Their grand plan fell apart.

The Famous Trial Ended with a Surprise Verdict

Authorities caught Burr near Mobile, Alabama in February 1807 after he tried to escape to Spanish Florida. Harman got caught too and spent 53 miserable days in Richmond Penitentiary waiting for trial.

The case became national news when Supreme Court Chief Justice John Marshall himself ran the proceedings.

Despite the government’s best efforts, both men walked free when prosecutors couldn’t prove the “overt acts” of treason required by the Constitution.

Money Troubles Followed Them Everywhere

The family lost nearly everything due to legal costs and property damage.

They tried starting over with a cotton farm in Mississippi but lost their remaining money within ten years. The family moved to Montreal where Margaret published poetry collections including “The Deserted Isle” in 1822.

They left for Europe in 1825, hoping for a fresh start, but their luck never improved. Harman died in Margaret’s arms on Guernsey in 1831.

Margaret Fought for Justice Until Her Last Breath

The stubborn widow returned to New York in 1842 with her sick son to ask Congress for payment for the damage done to their property. Henry Clay and other big political names backed her claim.

A Senate committee voted to approve payment to make up for the militia’s destruction of their beautiful mansion. Sadly, Margaret died on June 16, 1842, in a rundown New York apartment before getting a single penny.

She never saw justice for what happened.

The Island’s Story Lives On in American Legend

The original mansion burned to the ground in 1811, and the island sat empty for decades afterward.

West Virginia rebuilt the mansion between 1984 and 1991, turning the site into a historical state park that thousands visit each year.

In 1996, Margaret’s remains were moved from a New York cemetery to Blennerhassett Island, finally bringing her home.

Their dramatic story inspired operas, poems by Walt Whitman, and remains one of the most fascinating tales of ambition and downfall in early American history.

Visiting Blennerhassett Island Historical State Park, West Virginia

You can reach Blennerhassett Island by taking the Island Belle Sternwheeler from Point Park on 2nd Street in Parkersburg. The boat runs every half-hour and costs $12 for adults, $8 for kids 3-12.

Once there, mansion tours are $5 extra for adults, $3 for children, and horse-drawn wagon rides cost $12 adults, $10 children. Visit the Blennerhassett Museum at 137 Juliana Street for $4 adults, $2 children.

Open Tuesday-Sunday, May through October.

This article was created with AI assistance and human editing.

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