Complex sentence: On September 5, the Japanese linked up with the vanguard of the Czech Legion, a few days later the British and French contingents joined the Czechs in a effort to re-establish the east Front beyond the Urals; as a result the European allies trekked westwards.
Split into simpler sentences: On September 5, the Japanese linked up with the vanguard of the Czech Legion. A few days later the British and French contingents joined the Czechs in a effort to re-establish the east Front beyond the Urals; as a result the European allies trekked westwards.