Portus Lemanis was one of a number of coastal fortresses that were built during the late Roman empire known as the Litus Saxonicum (Saxon Shore) that were strategically placed along the English channel to provide military defense against would-be invasions from the continent. The constructions of such edifices reflected a current of fear that had begun to ripple through all the outposts of the Roman Empire as events in Europe reached a crisis point. 

Incursions by “barbarian” tribes had increasingly begun to break through the Roman lines of defense that were in turn weakened by the internal political and economical decline of Rome as an imperial power. In response to these rising threats, fortresses like Portus Lemanis were hastily built and occupied by Roman legionaries until the collapse of the Roman rule of in Britain in 407. In the decade that followed, the forts were gradually abandoned as the soldiers returned en masse to defend Rome from the imminent threat of marauding Germanic tribes.

As such, it is likely that Portus Lemanis was never actively used in defense against the Saxon tribes, who would eventually go on to invade, conquer, and colonize Britain in 440. During Roman times, the shoreline reached the position of the fort; however, in subsequent centuries, the land that was then submerged beneath the sea was reclaimed by humans due to a drainage system that helped to form what is now known as the Romney Marsh. 

Around the 13th century, a castle was constructed on land overlooking the Roman ruins. The castle never saw service in any military campaigns, and over many centuries it fell into periodical states of abandonment and decay until the First World War, whereupon it was used as a military barracks. In later history, the castle was used as a recording studio by Paul Mccartney’s band “Wings” to record the album Back to the Egg, along with other notable musicians from bands such as Led Zeppelin, Pink Floyd, and The Who.