There followed a correspondence between Mitre and Caxias in which the nominal commander-in-chief and his nominal subordinate argued the toss in the diplomatic language of the era; Mitre reminded him of the divers occasions when (he claimed) the navy had let them down. To descend below Curupayty again would look weak, as well as exposing the ironclads to battery fire, torpedoes and the risk of seizure by boarding. The ironclads stayed above Curupayty. According to George Thompson, if the ironclads had attempted to pass Humaitá at that point they would have faced only three 8-inch guns and about six 32-pounders; the other guns had been taken to reinforce Curupayty. The vessels were in enemy waters between two fires: Curupaty and Humaitá. The river fell, and would not reach maximum until sometime in 1868. It now became necessary to extend the Brazilian navy's lines of communication – already long by the standards of the day – even further. On 4 October 1867 the navy minister Affonso Celso de Assis Figueiredo by order established a liner service from Rio de Janeiro, Brazil exclusively to supply the Brazilian navy in Paraguay. Using four steamships, it had scheduled sailings, each way, on the 15th and 30th of every month. From Rio steamers stopped to coal at Montevideo, Uruguay and then steamed non-stop to Corrientes, Argentina to drop off correspondence before proceeding to the naval arsenal of Cerrito near the mouth of the River Paraguay. According to Affonso Celso's memoirs whatever the Brazilian vice-admiral asked for was promptly supplied from Rio. However, since the ironclads were cut off above the fort of Curupayty, the Brazilian government at once ordered the navy to build a supply line through the Chaco. The Chaco is the territory to the west of the River Paraguay. In those days it was claimed by both Argentina and Paraguay, but was uninhabited, except by a few nomads. In this coastal region it was almost impassable swamp. The supply line, named "Affonso Celso" after the minister of marine, ran between two improvised harbours on the west bank of the river, i.e. inland through the Chaco. They were dubbed "porto Palmar" (where the wooden vessels moored, below Curupayty) and "porto Elisário" (above); both were out of range of the Paraguayan guns.