Field post office

A Field Post Office (FPO) is a post office set up during time of war or when a military unit is on manoeuvres. It is set up 'in the field', hence the name, however, FPOs may be on land or at sea. Their use pre-dates the introduction of postage stamps.

History
FPOs have a long history. The first British FPO was in 1808 during the Peninsular War and in 1840 the British Army used a FPO during the first Chinese War.

FPOs were also used extensively during the Crimean War.

Terminology
In the United States a close equivalent is the Army Post Offices (APOs), the Air Force Post Offices (AFPOs) and the Fleet Post Offices (FPO in the U.S.).

In Hungary the head FPO is known as the tabori fopostahivatal while a normal FPO is an tabori postahivatal.

Equivalent terms are in use in most countries with Field Post Offices.

Collecting
Field Post Offices have special cancels and their mail is eagerly collected by philatelists, but the cancels are sometimes anonymised so that the place of posting is not revealed and this presents collectors with a challenge.