Pierre Joseph Rossier was a pioneering Swiss photographer whose albumen photographs, which include stereographs and cartes-de-visite, comprise portraits, cityscapes, and landscapes. He was commissioned by the London firm of Negretti and Zambra to travel to Asia and document the progress of the Anglo-French troops in the Second Opium War and, although he failed to join that military expedition, he remained in Asia for several years, producing the first commercial photographs of China, the Philippines, Japan and Siam. He was the first professional photographer in Japan, where he trained Ueno Hikoma, Maeda Genzō, Horie Kuwajirō, as well as lesser known members of the first generation of Japanese photographers. In Switzerland he established photographic studios in Fribourg and Einsiedeln, and he also produced images elsewhere in the country. Rossier is an important figure in the early history of photography not only because of his own images, but also because of the critical impact of his teaching in the early days of Japanese photography.