Located on the Rappahannock River near the head of navigation at the fall line, Fredericksburg developed as the frontier of colonial Virginia shifted west from the coastal plain into the Piedmont. The land on which the city was founded was part of a tract patented in 1671. The Virginia General Assembly established a fort on the Rappahannock in 1676, just downriver of the present-day city. In 1714, Lieutenant Governor Alexander Spotswood sponsored a German settlement called Germanna on the Rapidan River, a tributary of the Rappahannock upstream from the future site of the city. In 1716, he led an exploratory expedition westward over the Blue Ridge Mountains.