Representatives of the Knickerbocker Greys will appear Thursday in civil court as the Park Avenue Armory Conservancy takes its most aggressive step yet to remove the young cadets from its premises — a holdover eviction lawsuit.

The Knickerbocker Greys, America’s oldest after-school program, is a historic youth cadet corps, offering drill training to young men and women from elementary through middle school

The Park Avenue Armory Conservancy wanted the Greys out of the armory by June 1 this year. The conservancy says it will not have the space to host the Greys during its upcoming renovations, as it converts more of the 200,000 square feet into performing arts space. The basement where the Greys drill is to become a coat check, a renovation the Greys say is unnecessary.

The building previously served as the headquarters for New York’s 7th Regiment, which has fought in a dozen wars throughout America’s history, and the Greys have been based at the Armory since 1902. Greys alumni who drilled at the Armory include Mayor Lindsay, Vice President Rockefeller, and Douglas Fairbanks, Jr.

The Greys have not surrendered easily. Since the start of the school year, they have drilled at various sites in Midtown Manhattan without access to their home in the Armory’s basement. They’ve rallied outside the Armory’s recent gala fundraiser and a recent performance of Hamlet at the performing arts space.

On Independence Day, the young cadets were denied entrance to the Armory after a memorial service for the 7th Regiment’s fallen soldiers in the First World War. 

The Greys’ plight has drawn the support of prominent elected officials across the city — including Representative Carolyn Maloney. The Upper East Side community board in which the Armory is based has rallied around the Knickerbocker Greys, devoting time in multiple meetings to the Greys’ plight and passing in May a resolution in support of the young cadets.

At a community board meeting in May, Ms. Maloney spoke via Zoom to applaud the Greys for “instilling the values of leadership, responsibility, commitment, and citizenship” in thousands of local children. Ms. Maloney also endorsed the Greys’ right to continue using the Armory — which she said was “a purpose of the Armory, really.”

The Greys and their supporters have urged Governor Hochul to offer a direct lease with the state that would allow the group to circumvent the Armory Conservancy. Two other tenants of the Armory, the National Guard and Lenox Hill Women’s Shelter, have their leases with the state.

The Greys are currently crowdfunding on GoFundMe for the cost of legal fees, with a goal of raising $30,000 to procure legal counsel.

The Armory and its counsel did not respond to requests for comment.