Influence of the House of Representatives on the government increased, and the party cabinets of the 1920s brought Japan apparently closer to a parliamentary system of government, and there were several reforms to the upper house in 1925. However, the balance of powers between the two houses and the influential role of extra-constitutional actors such as the Genrō (who still selected the prime minister) or the military (that had brought down several cabinets) remained in essence untouched. Within a year of the Japanese invasion of Manchuria in September 1931, a series of assassinations and coup attempts followed. Party governments were replaced by governments of "national unity" ("kyokoku itchi") which were dominated by nobles, bureaucrats and increasingly the military.