The River Arno Project
Background
All throughout the 14th century, there were periods of intense hostility between Pisa and Florence. A great commercial center, Florence relied on the foreign trade that reached the city by means of the River Arno, and therefore wanted sole control of the river. Standing in their way was the city of Pisa, proudly situated at the mouth of the Arno.
Around 1498 the Florentine army began yet another campaign to capture Pisa, aided by French mercenaries paid for by the Florentine taxpayer. By 1503, the citizens were refusing to spend any more money on war. Without sufficient troops to mount a full attack, the Florentines explored alternative methods. One such idea was to divert the River Arno around the city of Pisa, subsequently depriving them of both their water supply and their harbor. Two engineers submitted ideas for this feat: Colombino and Leonardo da Vinci.