So he wrote the King that he might rely upon him to join him with 40,000 Cossacks in Little Russia.

He thought it would be an easy matter to turn the irritated Cossacks from the Tsar.

They were restive under the severity of the new military _regime_, and also smarting under a decree forbidding them to receive any more fugitive peasants fleeing from serfdom.

But he had miscalculated their lack of fidelity and his own power over them.
It was this fatal promise, which was never to be kept, that probably lured Charles to his ruin.

After a long and disastrous campaign he met his final crushing defeat at Poltova in 1709.