The Argentine general Lucio N. Mansilla set up three thick metal chains suspended from 24 boats completely across the river, to prevent the advance of the European fleet. This operation was under the charge of an Italian immigrant named Filipo Aliberti. Only three of these boats were naval vessels; the rest were requisitioned barges whose owners received a compensation in case of loss. Aliberti was the master of one of the boats, the "Jacoba", sunk in the battle. At least 20 boats and barges were lost in the chain barrage at Obligado.