In 1808 Napoleon entered Spain to attack Portugal. French forces remained in Spain for the next five years. Under British pressure the French retreated to San Sebastian.
     San Sebastian stands on a peninsula, projecting northward into the Bay of Biscay. The fortress was of a basic square design covering the flat area of the peninsula and fully enclosing the town. In July 1818 a British army under the command of General Graham placed the city under siege.
     On August 31 an attempt to relieve the siege was repelled by Spanish troops at San Marcial and the fortress fell to the British. Because the townspeople were believed to support the French the town and fortress were sacked and burned.
     The stamp commemorates the battle of San Sebastian in 1813, and the 150th anniversary of the rebuilding of the town in 1863.