Up the valley of this river they travelled, until they reached the head, where, at the Valley of Lagoons, they crossed the watershed on to the waters of the Gulf of Carpentaria. Here, for some unknown reason, Leichhardt went far too much to the north, which necessitated a long detour around the south-eastern corner of the Gulf. It was while they were retracing a southern course along the eastern shore of the Gulf that the naturalist Gilbert met his fate. Up to this time they had been so little troubled with the natives that they had ceased almost to think of a possible hostile encounter with them. This fancied immunity was broken in a most tragic manner on the night of the 28th of June, 1845. It was a calm, quiet evening, and the party were peacefully encamped beside a chain of shallow lagoons. The doctor was thinking out his plans for the next few days, Gilbert was planting a few lilies he had gathered, as was his nightly habit when any flowers were available. Roper and the others were grouped around the fire warding off the attacks of the mosquitoes. Suddenly about seven o'clock a shower of spears was thrown among the unarmed men, and Gilbert was almost instantly killed, Roper and Calvert being seriously wounded. The whites rushed for their guns, but unfortunately not one weapon was ready capped, and it was some time before any of them could be discharged, when a volley caused the blacks to scamper off. It is most astonishing that the whole of the members of the party were not cut down in one dreadful massacre. The body of the murdered naturalist was buried at the fatal camp, but the grave was left unmarked, and a large fire built and consumed above it to hide all traces of it from the natives. The river where this sad mishap occurred now bears the name of Gilbert.