Complex sentence: The forts were destroyed by the bombardment of the super-heavy artillery and much of the Belgian 4th Division withdrew to the south, the last of the Belgian fortress troops were forced to surrender on 25 August.
Split into simpler sentences: The forts were destroyed by the bombardment of the super-heavy artillery and much of the Belgian 4th Division withdrew to the south. The last of the Belgian fortress troops were forced to surrender on 25 August.