Axis, coalition of countries headed by Germany, Italy, and Japan, 1936–45 (see World War II). The expression "Rome-Berlin axis" originated in Oct., 1936, with an accord reached by Hitler and Mussolini. The Axis was solidified by an Italo-German alliance in May, 1939. This was extended (Sept., 1940) by a military alliance among Germany, Italy, and Japan—the so-called Berlin Pact, to which Hungary, Romania, Bulgaria, Slovakia, and Croatia adhered later. The related Anti-Comintern Pact (see Comintern), originally concluded between Germany and Japan in 1936, later had as adherents, besides the Berlin Pact nations, Spain, Denmark, Finland, and the puppet governments of Manchukuo and Nanjing.