Complex sentence: FC Saarbrücken was one of a number of sides forced out of German football, but unlike other clubs they did not play in the puppet league: instead the strong side became part of the French second division as FC Sarrebruck.
Split into simpler sentences: FC Saarbrücken was one of a number of sides forced out of German football, but unlike other clubs, they did not play in the puppet league. Instead, the strong side became part of the French second division as FC Sarrebruck.