Robert Erskine (inventor)

In 1776 during the American Revolutionary War he designed an underwater cheval-de-frise that was installed across the Hudson River at the north end of Manhattan to prevent passage of British ships upriver.

That year the owners of an ironworks near Ringwood, New Jersey, hired Erskine to replace Peter Hasenclever as ironmaster.

Erskine designed a tetrahedron-shaped marine cheval-de-frise, a defensive barrier of pointed logs strung together abreast the river to prevent warships from sailing upriver.

George Washington was impressed with Erskine from the moment they met in 1777, and appointed him to the post of Geographer and Surveyor General of the Continental Army.

His maps of the region, showing roads, buildings, and other details, were of much use to General Washington and remain historically valuable today.

[1][2] Erskine also kept the Ringwood ironworks in operation, supplying critical munitions and materials to Washington's army.