He immediately sent to his brother-in-law ten thousand cavaliers.

The Kings of Bohemia and of Poland also entered into an alliance with the exiled prince, and in person led the armies which they contributed to his aid.

A war of desperation ensued.

It was as a conflict between the tiger and the lion.
The annals of those dark days contained but a weary recital of deeds of violence, blood and woe, which for ten years desolated the land.
All Russia was roused.

Every feudal lord was leading his vassals to the field.