However, the liberals were still strong in the west and north. On the Isthmus four insurrections had broken out from October, 1899, to September, 1901, and though each had been promptly suppressed, in 1902 the liberals were able to make a last great effort to establish themselves at Panama. They had considerable forces near the mouth of the Magdalena, and gunboats on the Pacific. The secure possession of the Isthmus would have enabled them to reinforce this Magdalena army, cut off Marroquin from the sea, and undertake a campaign against the interior. At first all went well for them; their gunboats captured the government's vessels on the Pacific side; they concentrated a respectable army there and finally defeated and captured two thousand of Marroquin's troops at Agua Dulce, near Panama. But this was their last success. Marroquin poured reinforcements into Colon, and though the American admiral at first refused to allow them to be transported over the railroad to Panama, permission was granted when it became evident that there would be no fighting near the line. News came of the defeat of the liberal army near the Magdalena, and General Herrera, the victor at Agua Dulce, found himself isolated. In desperation he sent an expedition in October which surprised and captured Colon, but French and American marines were promptly landed to prevent fighting in that city. The expedition had no alternative but to surrender, and a few days later General Herrera with the main body capitulated on the Pacific side. The three years of war left Colombia in frightful demoralisation. The victorious government was little better off than the defeated liberals. Commerce and industry had been prostrated; revenues had dwindled to nothing; the paper currency was worth less than one per cent. The exhaustion of its adversaries, not its own strength, enabled Marroquin's government to continue in power. In such a situation the administration welcomed the opportunity which now offered of renewing the building of the Isthmian canal. The United States government determined to undertake this great work itself, and finally decided in favour of Panama as against the Nicaragua route. Forty million dollars was agreed upon as a just price for the work already done by the French Company, and nothing remained but to obtain Colombia's consent to the transfer. The civil war helped to delay the negotiation of a satisfactory treaty, but as soon as it was over the Marroquin administration lost little time in coming to an agreement with the United States. Colombia was to receive a bonus of ten million dollars for consenting to the transfer and enlarging the terms of the original concession; her sovereign rights were reserved and guaranteed, although she agreed to police and sanitary control of the canal strip by the United States.