This episode covers 55 BCE and centers around Julius Caesar’s first invasion of Britannia.
Caesar is in Britannia with the Seventh and Tenth Legions, has fought a single battle, and has subsequently received the surrender of the surrounding tribes. But basically after that first landing battle, the Brits had had enough. This cold and eerily silent group of foreigners were just too well armed, too well organized, and just too effective in the battlefield. Peace was the only way to deal with people such as this.
So for four days the brits from the surrounding area came to Caesar to surrender.
And on the fourth day, Caesar’s cavalry finally set sail. Remember them? The 500 cavalry that embarked at a different port from the rest of Caesar’s army? Yeah, they were finally on their way… and that was really good news because those Britons had chariots, and that made them irritatingly speedy. While Caesar had won on the battlefield, he was probably all too aware that he was still exposed so long as the Britons could quickly move throughout the island unchecked. And frankly, until the Romans could ride the Britons down, he wouldn’t be able to stamp out any further resistance… and despite whatever legal pretenses he was giving, that was essentially what Caesar wanted to accomplish here. An end to british resistance and consequently, an end to their interference with his affairs in Gaul.