Complex sentence: Meanwhile, the Saxon army under Schulenburg was defeated by Rehnskiöld at the Battle of Fraustadt, which would result in a Swedish invasion of Saxony and the Treaty of Altranstädt (1706) where Augustus had to renounce all his claims to the Polish throne.
Split into simpler sentences: Meanwhile, the Saxon army under Schulenburg was defeated by Rehnskiöld at the Battle of Fraustadt. This would result in a Swedish invasion of Saxony and the Treaty of Altranstädt (1706) where Augustus had to renounce all his claims to the Polish throne.