[9] By 1863, the demesne was divided in two, with a deer park in the north and the castle, pleasure grounds, farm and two artificial lakes to the south.
During the First World War, Royal Naval Air Service airships were based at Johnstown Castle, and were primarily used to deal with the U-boat threat, but with limited success.
On 1 May 1944, the contents of the castle were sold off at a public auction lasting five days and conducted by Jackson Stops & McCabe.
It is managed by the Irish Heritage Trust under curator Matt Wheeler, and work on conserving and restoring the building continues.
[citation needed] A servants' tunnel, 86 metres (282 ft) in length, runs from the meat house to the kitchens.