Archaeologists have discovered only the second known port of Roman Britain, where soldiers would have arrived in numbers from the Mediterranean to aid in the fight against some of the most stubborn and hostile of all the tribes they had to face.

Over the last year, archaeologists have been digging near the Roman fortress of Caerleon, just north of Newport, south Wales, and have made some remarkable discoveries. On Tuesday, the site was declared the only known Roman British port outside London.

"It is extremely exciting," Peter Guest, leading the excavation team from Cardiff University, said. "What we have found exceeds all expectations. It now seems clear that we're looking at a new addition to our knowledge of Roman Britain."...