In 1867 during the Paraguayan War some ironclad vessels of the Brazilian navy became trapped on the River Paraguay between the enemy Paraguayan forts of Curupaty and Humaitá. To keep them supplied with fuel, ammunition and provisions the Brazilian ministry of marine ordered an emergency military railway to be built through the almost impenetrable coastal region of the Chaco. The sleepers of this line almost floated over the boggy ground. This supply line was known as the "Affonso Celso", and sustained the ironclads in their precarious position for six months, until they were able to dash past the Fortress of Humaitá in an incident known as the Passage of Humaitá.