Siege of Portsmouth
1642 CE.
Shown on the map at 50.806°, -1.087°.
The siege of Portsmouth was the siege of a Royalist garrison in Portsmouth by a Parliamentarian force conducted in the early part of the First English Civil War. The siege resulted in Portsmouth falling to Parliament after a little under a month of conflict.
Text from the Wikipedia article Siege of Portsmouth, licensed CC BY-SA 4.0.