Around 2,400 years ago, before the emergence of the Roman empire, a small armada of boats approached the island of Als off the coast of southern Jutland in modern-day Denmark. The armada carried around 80 warriors armed with spears and shields. Some of them were officers, and these men carried iron swords.
The seafarers had travelled across what is now the Baltic Sea in sleek plank boats some 20 metres long. The planks were sewn together as boats at this time did not use metal nails, and the seams were caulked (waterproofed) with tar.
