Complex sentence: Most of these vehicles were used by the occupation forces in France; three ZT4s would in May 1945 be discovered by the Soviet forces entering Prague; they had been captured by the Czech resistance and turned against their former owners.
Split into simpler sentences: Most of these vehicles were used by the occupation forces in France. In May 1945 three ZT4s were discovered by the Soviet forces entering Prague; they had been captured by the Czech resistance and turned against their former owners.