The second British expedition which entered the Cameroons from a more westerly point along the Nigerian frontier occupied, after slight resistance, the German station of Nsanakong a few miles from the border, where a week later the Germans attacked in force at two o'clock in the morning. The British resisted stubbornly, but, having exhausted their ammunition, the garrison tried to cut their way out with the bayonet. The British lost three officers, while large numbers of native soldiers were killed or made prisoners. The remainder, escaping to the bush, after many hardships found their way back to Nigeria. Another British expedition from Calabar, near the coast, occupied Archibong, August 29, 1914, while about the same time a German force took possession of the Nigerian station of Okuri. The British had failed by land; they were more successful on the sea, as will be seen in the chapter on Naval Operations. On September 4, 1914, an attempt was made by the Germans to wreck the British gunboat _Dwarf_, which with the cruiser _Cumberland_ was watching German ships in the Cameroon estuary. The German merchantman _Nachtigal_ tried later to ram the same gunboat and wrecked herself with a loss of 36 men. Further attempts to destroy the _Dwarf_ also failed. The British now taking the offensive cleared the channel for three miles, where the Germans had sown mines and sunk 10 or 12 steamboats to obstruct the waterway to Duala, the capital of the Cameroons. H.M.S. _Challenger_ and five troopships joined the _Dwarf_ and _Cumberland_ on September 26, 1914, and, moving on Duala, bombarded the town. On September 27, 1914, the Germans offered to surrender Duala unconditionally, and on September 28, 1914, Brigadier General C. M. Dobell came ashore and took it over. About the same time a battalion landing at Bonaberi, across the river from Duala, capitulated after some desultory fighting. The wireless station at Duala was found to have been wrecked, but the British took several hundred prisoners, captured 8 merchantmen with valuable cargoes and the German gunboat _Soden_, which was at once put into commission in the British navy. While the British were successful around Duala, a French force by sea from Libreville, French Congo, escorted by their warship _Surpris_, attacked _Ukoko_ on Corisco Bay, south of the Cameroons, during which the armed vessels _Khios_ and _Itolo_ were sunk. The Allies had captured the chief port and controlled the coast, but the most difficult work lay before them in the mountainous and almost roadless region still to be conquered. The retreating Germans occupied a defensive position on a river at Japona, where on October 8, 1914, a French column came up with them, forced a bridge, and compelled them to continue their retreat.