After surviving Boudicca's Rebellion, the Roman province of Britannia was more or less stagnant - until a general arrived with an ambition to complete the conquest. Gnaeus Julius Agricola came to Britain in 77 AD with the ambition to lead the legions into the wild northern regions of Caledonia, a.k.a. Scotland, all the way to the ends of the known earth. And the only reason we know about this campaign is Agricola's son-in-law, the historian Tacitus, who made sure that his wife's beloved father wouldn't become an unknown soldier.

Sources: https://www.unknownsoldierspodcast.com/post/episode-63-furies-of-britannia-sources-and-maps