Who built forts on land claimed by virginia, prompting the first battles of the french and indian war?

The answer is France

It is known as the Franco-Indian War (1754-1763) as part of the Seven Years War developed in North America. The name refers to the two main enemies that the British faced: French and different tribes of Native Americans.

The war was the result of tensions between British and French due mainly to the expansionist pretensions of the colonies of both countries. Questions such as conflicts between the natives, who were forced to request protection from one or another colonial empire, also came into play.