The canal was initiated by
Maximilien de Béthune, duc de Sully, with support from
Henry IV in order to develop the
grain trade, and to reduce food shortages. Its construction started in 1604 and was completed in 1642. Between 6,000 and 12,000 labourers worked on this canal which connects the basins of the rivers
Loire and
Seine.
Hugues Cosnier obtained the contract to build the second canal crossing a watershed in Europe, involving many more locks than on the first. It was thus necessary to use locks. A staircase of seven locks was built in
Rogny-les-Sept-Écluses. (This was bypassed in 1887 but is preserved as an ancient monument and floodlit at night.) After
Henri IV's assassination,
Hugues Cosnier had to give up work in 1611. In 1638,
Guillaume Boutheroue and
Jacques Guyon applied to resume work, and received letters patent from
Louis XIII for this purpose. They created with other nobles the
Compagnie des seigneurs du canal de Loyre en Seine and work was completed by 1642. Reservoirs were dug to supply the approximately 2000 cubic meters of water displaced at each lock. They include the reservoirs of Turfs, Chesnoy, Grand-rû, Tilery, Du Chateau, Cahauderie, Beaurois, the Bourdon reservoir, and the Moutiers reservoir on the Loing. The original source of water was the
Étang de la Gazonne. ==Usage==