Complex sentence: Nevertheless Saito's administration was one of the longer-serving ones during the inter-war period, and stayed in office until July 1934; even after it finished, Saito continued to be an important figure in politics.
Split into simpler sentences: Nevertheless Saito's administration was one of the longer-serving ones during the inter-war period. After resigning in July 1934, Saito continued to be an important figure in politics.