When the Christiansholm Festning was built circa 1672, it stood on a small island off the shore of Kristiansand in the East Harbor. A tall, stone bastion still surrounds its base. The garrison was only tested in battle during the Napoleonic Wars when it was attacked in 1807 by two Royal Navy ships including the HMS Spencer. When the British succeeded in occupying the fort, they tried to destroy it with dynamite. Their plan literally backfired when a delayed fuse unexpectedly exploded, killing four seamen.