In 1753, the Masonian Proprietors of Portsmouth, New Hampshire, granted the area now called New London as "Heidelberg".

Although it appears on some New Hampshire maps, the township was never settled, and the 1753 grant lapsed into default.

These proprietors were led by Jonas Minot of Concord, Massachusetts, but the others were Scotch-Irish immigrants living in Londonderry, New Hampshire.

Instead they recruited settlers to build roads, mills, schools, and a church—all increasing the value of their land holdings.

The township proprietors soon began a long, systematic process of subdividing and selling their properties at great profit.

In 1807, the northern half of New London was annexed, merged with an area called "Kearsarge Gore", and then incorporated as the town of Wilmot, New Hampshire.

The highest point in town is Morgan Hill, approximately 1,770 feet (540 m) above sea level.

The town is crossed by Interstate 89, which serves New London with two exits, and by New Hampshire Routes 11, 103A, and 114.