In 1845, the Baltic German explorer
Alexander von Middendorff visited the lands on the Amur and wrote a report on behalf of the Russian government. The navigator reached the mouth of the Amur in 1847, but failed to locate a deep-water entrance. In the same year,
Nikolay Muravyov was appointed Governor-General of East Siberia. Before leaving for Irkutsk, Muravyov arranged for the creation of an "Amur Committee" to coordinate work in the area. In 1849, he traveled overland to
Okhotsk, and from there went on to
Petropavlovsk on
Kamchatka. This would result in the main Russian naval center in the east relocating from Okhotsk to Petropavlovsk. From 1849 to 1855, a Russian expedition commanded by Lieutenant-Captain
Gennady Nevelskoy explored the Pacific coastline, the island of Sakhalin, and the outlet of the Amur. In 1849, Nevelskoy and his men sailed through a section of the Amur, and then south through the
Strait of Tartary, proving that Sakhalin was an island, a fact which was kept a military secret. In 1850, Nevelskoy founded the settlement of
Nikolayevsk on territory claimed by the Qing. The Russian foreign minister
Karl Nesselrode attempted to prevent the settlement, but Czar
Nicholas I in turn overruled him, declaring "where once the Russian flag is raised, it must not be lowered". Over the next three years, Nevelskoy established various other forts on territory claimed by the Qing around the mouth of the Amur. To establish a military force, Governor-General Muravyov created the
Transbaikalian Cossacks by arming 20,000 serfs from local mines. From May to June 1854, he and 1,000 men sailed down the Amur to Nikolayevsk, and the Manchu governor at
Aigun had no choice but to allow them to pass. News of the
Crimean War reached China in July 1854. In September, an Anglo-French naval force was defeated at the
Siege of Petropavlovsk. Judging that Petropavlovsk could not be reliably defended further, Muravyov ordered Rear Admiral
Vasily Zavoyko to move his forces into the Amur area instead. In May 1855,
Charles Elliot's force found Zavoyko at De Kastri Bay, south of Cape Nevelskoy on the Strait of Tartary. Under the cover of fog, Zavoyko withdrew northward to the mouth of the Amur, a move that baffled the British, who were still under the impression that Sakhalin was connected to the mainland. That same year, Muravyov sent a 3,000-man force down the course of the Amur, including those intended as settlers. The Qing declared this to be illegal, but did not act. 1855 also saw Russia and Japan sign the
Treaty of Shimoda, which temporarily resolved the conflict regarding Sakhalin and the
Kuril Islands. The
Second Opium War broke out in 1856; two years later, the British and French captured
Guangdong. When news of this reached Saint Petersburg,
Alexander Gorchakov, the foreign minister who had replaced Nesselrode, decided that it was time to "activate Russian Far Eastern Policy". Muravyov was given plenipotentiary powers, and Admiral
Yevfimiy Putyatin—who had represented the Russians in the earlier treaty negotiations with Japan—was sent to Beijing to negotiate a more favorable relationship. Over 1856 and 1857, Muravyov sent more settlers down the Amur. In 1858, he traveled its course himself; his instructions were to not use force except in rescuing captives. Upon reaching Aigun, he presented the local governor with what would become known as the
Treaty of Aigun. The treaty ceded all territories north of the Amur to Russia, and declared the area east of the
Ussuri River and south of the Amur to be a Sino-Russian condominium until further negotiations could take place. The local governor signed the treaty, but the Qing government in Beijing refused to ratify it, declaring it to be invalid. Muravyov continued down the Amur, founding
Khabarovsk at the mouth of the Ussuri. In September 1858, Czar
Alexander II promoted him to a full generalship, and granted him the suffix "Amursky". The following year, General Muravyov-Amursky sent an expedition to explore the Pacific coast, which reached as far south as present-day
Vladivostok. == Putyatin, Ignatyev, and the Convention of Peking (1860) ==