Complex sentence: Then in 1643, soldiers from the Lorraine came and brought war back into the region; in 1644, the imperial army arrived and in 1645, it was the French under Turenne.
Split into simpler sentences: Then in 1643, soldiers from the Lorraine came and brought war back into the region again. In 1644, the imperial army arrived and in 1645, it was the French under Turenne.