At this point, in 1707, Peter offered to return everything he had so far occupied (essentially Ingria) except Saint Petersburg and the line of the Neva, to avoid a full-scale war, but Charles XII refused. Instead he initiated a march from Saxony to invade Russia. Though his primary goal was Moscow, the strength of his forces was sapped by the cold weather (the &lt;a href="Great%20Frost%20of%201709"&gt;winter of 1708/09&lt;/a&gt; being one of the most severe in modern European history) and Peter's use of scorched earth tactics. When the main army turned south to recover in Ukraine, the second army with supplies and reinforcements was intercepted and routed at Lesnaya—and so were the supplies and reinforcements of Swedish ally Ivan Mazepa in Baturyn. Charles was crushingly defeated by a larger Russian force under Peter in the Battle of Poltava and fled to the Ottoman Empire while the remains of his army surrendered at Perevolochna.