At about the same time, his slightly older brother, John Augustine Washington III, built the Blakeley mansion about 600 yards away and facing Claymont.

Both of the young men were captured in Claymont Court during Christmas furlough (holiday leave) by Union Army troops led by George Custer.

As the mansion and larger estate was unoccupied for a few years at a time, the property began to deteriorate due to reduced maintenance, and the farming operations halted.

Claymont operated as a self-sustaining farm, differing from plantations in the deeper American South, which had been based on producing commodity crops.

Before the Civil War, the owners held nearly one hundred enslaved people as well as a couple dozen free workers to accomplish all the work.

The transition to the use of free labor, especially during decades of continuing decline in the agricultural market, made it difficult for owners to make enough revenue to keep the estate operational.

In 1973, Claymont was added to the National Register of Historic Places, a US government list of buildings and structures deemed worthy of preservation.

While Bennett was alive, Claymont operated as a nine-month Fourth Way school focused on his specific teachings, which dealt with techniques of self-reflection, self-development, and spirituality, a systems discipline called Systematics, and achieving a sustainable relationship with nature.

After Bennett died in December 1974, the nine-month basic course project continued for a few years under the direction of his students but was eventually discontinued.

Its residential rooms were retrofitted with showers; utilities were updated for hot water, electricity, natural gas, and Wi-Fi.

Claymont has received grant money for restoration through the 1772 Foundation, Save America's Treasures, Jefferson County Commission, and individual donations.

The Claymont Society works in tandem with the National Park Trust to lobby for continuing preservation grants.

Among recent restorations, the mansion has a completely rebuilt second-floor veranda, new support beams for the main ballroom, and new window seals and gutter systems.