Landguard Fort 
“Landguard Fort is the site of the last opposed seaborne invasion of England in 1667 and the first land battle of the Royal Marines.…” – official site
Ease by public transport:
Unknown
“Landguard Fort is the site of the last opposed seaborne invasion of England in 1667 and the first land battle of the Royal Marines.…” – official site
Ease by public transport:
Unknown