Complex sentence: Frederick sent Wedel to thwart the Russian advance into Brandenburg with 28,000 men; these were not enough, but due to Wedel's poor management and aggressiveness--he was ordered to attack a Russia army twice his size--they were crushed at the Battle of Kay.
Split into simpler sentences: Frederick sent Wedel to thwart the Russian advance into Brandenburg with 28,000 men; these were not enough. Due to Wedel's poor management and aggressiveness--he was ordered to attack a Russia army twice his size--they were crushed at the Battle of Kay.