The Fossa Eugeniana or Spanish Rhine-Maas canal was a large-scale ambitious project of the Thirty Years' War planned by the then Spanish regent in Brussels, Isabella Clara Eugenia, after whom it was named, during the years 1625–1629. It consisted of a fortified canal intended to blockade by river the United Provinces, in order to divert trade from the Rhine just south of Wesel and reroute it to Venlo on the Maas, in Spanish territory. It was also known as the Spanish Rhine-Maas canal, when at the time Spanish garrisons in north-western Germany reached their maximum extent, amounting to around fifty fortresses and forts. It was 4.30 metres (14.1 ft) wide and 60 kilometres (37 mi) long.