Longmoor Camp is a British Army camp close to the A3 and A325 roads in and around the settlements of Longmoor, Liss and Liphook in Hampshire, England. The main street of the Longmoor part of the camp is built on an ancient Roman road, the Chichester to Silchester Way, while the village of Greatham lies to the west. The combined camp and training area covered 1,783 hectares (4,410 acres) of wooded areas, heath, wetlands and hard standings. Longmoor Camp and the training areas are still active, and maintained by the Defence Infrastructure Organisation.

The camp is occupied by the Royal Military Police Close Protection Unit.

In 1863, the War Department had required additional training grounds for British Army troops. They purchased tracts of land totalling 781 acres (316 ha) from Her Majesty's Woods, Forests and Lands at Hogmoor Inclosure and Longmoor on the Surrey/Hampshire borders. However, the Army's main barracks were at Aldershot Garrison, requiring a 20 miles (32 km) march or expensive railway journey to access the new training grounds. This distance also necessitated an overnight stay, most often accomplished by pitching tents east of the A325 road.

The decision was hence made to build two permanent camps close to Woolmer Forest. The proposal was to construct 140 wooden huts on each site, each 72 feet (22 m) long and 21 feet (6.4 m) wide, giving a combined accommodation for 5,000 men. The first site was laid out in 1899 by the Highland Light Infantry, under the command of the Royal Engineers. This became Bordon Camp, an area of approximately 1 mile (1.6 km) long by .5 miles (0.80 km) wide. With construction curtailed on the first site by the Second Boer War, the Army began work at Longmoor Camp. After being laid out by the Royal Engineers in August 1900, construction materials were transported from Bentley railway station, with the resultant damage by commercial traction engines to the public roads bringing about the first trial of pneumatic tyred lorries to the British Army.

In November 1902, the War Department bought the 550 acres (220 ha) Broxhead Warren estate from Sir David Miller Barbour for £20,000, added to by an additional purchase for £18,000 in early 1903. It was decided that the camps at Longmoor would be named after successful battles and locations from the Boer War. The officers' accommodations were named after Seven Years' War commanders, Amherst and Wolfe.

In May 1903, the 1st Battalion of the Argyll and Sutherland Highlanders and the 2nd Battalion of the Wiltshire Regiment were the first to occupy Longmoor camp. However it was built on boggy ground and the troops immediately began to complain of problems and the medical officers of ill health. A decision was immediately made by the War Department to move 68 of the Longmoor huts to the Bordon camp site, between 4 miles (6.4 km) and 6 miles (9.7 km) away.

When the Canadian Army was looking for a European base, the British Army offered them Bordon and Longmoor Military Camps, which they took over entirely from September 1939 under a British officer commanding the local service and civilian personnel.

Longmoor housed 5 Railway Training Regiment Royal Engineers which in 1948 became 16 Railway Training Regiment and remained at Longmoor until the railway role was taken over by the Royal Corps of Transport in 1965. Longmoor Military Railway finally closed on 31 October 1969.