In the course of his Gallic Wars, Julius Caesar invaded Britain twice: in 55 and 54 BCE. On the first occasion Caesar took with him only two legions, and achieved little beyond a landing on the coast of Kent. The second invasion consisted of 628 ships, five legions and 2,000 cavalry. The force was so imposing that the Britons did not dare contest Caesar's landing in Kent, waiting instead until he began to move inland. Caesar eventually penetrated into Middlesex and crossed the Thames, forcing the British warlord Cassivellaunus to surrender as a tributary to Rome and setting up Mandubracius of the Trinovantes as client king. Caesar included accounts of both invasions in his Commentarii de Bello Gallico, with the first significant first-hand descriptions of the people, culture and geography of the island. This is effectively the start of the written history, or at least the protohistory, of Britain.