Military reserve force

During peacetime, reservists typically serve part-time alongside a civilian job, although most reserve forces have a significant permanent full-time component as well.

During wartime, reservists may be kept in service for months or years at a time, although typically not for as long as active duty soldiers.

In countries with conscription, such as Switzerland and Finland, reserve forces are citizens who have completed active duty military service but have not reached the upper age limit established by law.

For example, the half-pay system in the British Army provided the country with trained, experienced officers not on active duty during peacetime but available during wartime.

Although contemporaries debated the effectiveness of the British militia, its mobilization in several conflicts increased Britain's strategic options by freeing regular forces for overseas theaters.

On 9 July 1807, in the Treaties of Tilsit, Napoleon forced Prussia to drastically reduce its military strength and cede large amounts of territory.

The Krumpersystem, introduced to the Prussian Army by military reformer Gerhard von Scharnhorst, gave recruits a brief period of training which could be expanded during wartime.

Reservists and reserve officers are occasionally called up for refresher exercises, but receive no monthly salary or position.

Reservists can provide garrison duty, manning air defense, internal security and guarding of important points such as supply depots, prisoner of war camps, communications nodes, air and sea bases and other vital areas, freeing regular troops for service on the front.

In countries with a volunteer army, reserve enlisted personnel are soldiers, sailors, and airmen who have signed contracts to perform military service on a part-time basis.

In countries with conscription, reserve enlisted personnel are soldiers, sailors, and airmen who are not on active duty and have not reached the upper age limit established by law.

Reserve soldiers, sailors, and airmen are subject to mandatory short-term military training in peacetime, as regulated by law.

Reserve soldiers, sailors, and airmen have civilian status, except for military training in peacetime and wartime mobilization.

Reserve enlisted personnel are not on active duty, have not signed a contract to perform military service as reservists, and have not reached the upper age limit.

Reserve non-commissioned officers are not on active duty, have not signed a contract to perform military service as reservists, and have not reached the upper age limit.

In countries with conscription, reserve warrant officers are military personnel with the relevant rank who are not on active duty and have not reached the upper age limit.

Preparations to institute a call-up (obvious to adversaries) can display determination, boost morale, and deter aggression.

The skills of reservists have been valuable in peacekeeping because they can be employed for the reconstruction of infrastructure, and tend to have better relations with the civilian population than career soldiers.

Reservists are usually provided with second-line equipment which is no longer used by the regular army, or is an older version of that in current service.

Reservists who combine a military and civilian career, such as members of the United Kingdom's Army Reserve, experience time demands not experienced by regular troops which affect their availability and length of service.