By 56BC (we think) the Channel Islands were part of the Roman Empire. That doesn’t mean that the islands were full of Italians, it was the same people living here as before but Rome was in charge. Guernsey was first to take to Roman ways and there are over 50 places in that island where Roman pottery or roof tiles have been found. The Roman name for the island seems to have been “Lisia” which suggests it was a swampy place. St Peter Port was a small town and around the year 280, a Roman ship caught fire and sank in the harbour. You can see its wreck on show in Guernsey.
Alderney seems to have had a Roman village of some sort down on Longis Common. The Roman army or Roman navy set up a base somewhere near Longis too. We have found pottery of a kind used by the Roman soldiers that dates between 70 and 160 AD. Roman warships had both sails and oars and Longis Bay is a good place to base a few of them. From Alderney they could keep an eye on ships sailing past the French coast and stop pirates.
The islands were peaceful for 300 years, but trouble was brewing. After AD 250, ‘barbarians’ from the east started attacking the Roman Empire. A new fort was built to protect Longis harbour. This is now called the Nunnery and you can still walk on its walls where Roman soldiers walked.
Rome was burned by barbarians in the year 410 and it all started to go horribly wrong. A tribe called the Franks defeated the Romans in France and by the year 475 we were not ruled by Rome any more. And we don’t really know what happened next…