The Spanish Civil War broke out in 1936. Britain refused to become involved and Italy and Germany gave military support to the Spanish dictator, Francisco Franco. Franco's victory meant an ally for the Rome-Berlin Axis. In 1937 Japan began an invasion of China, which threatened British trade and investment. The British government followed a policy of 'appeasement', agreeing to the supposedly more 'reasonable' German demands.
The other wing of British policy sought to resume harmonious relations with Italy. In April 1938 an Anglo-Italian agreement acknowledged Italy's seizure of Abyssinia (modern Ethiopia) in exchange for reduction of Italian troops in Spain.
In 1938, despite being forbidden under the Treaty of Versailles, Hitler aimed to unify Austria and Germany. Hitler forced the Austrian Chancellor, Kurt Schuschnigg, into appointing the virulent Nazi, Artur Seiss-Inquart, as Minister of the Interior. In March 1938 Germany annexed Austria without substantial objection from Britain or France.
Hitler now turned his attention to Czechoslovakia. Here the position was more complicated because France and Russia had treaties with Czechoslovakia. On 29 and 30 September 1938 Mussolini brokered a conference of Germany, Britain, France and Italy at Munich. Germany was to occupy Sudetenland in Czechoslovakia, and the British Prime Minister, Neville Chamberlain, signed an Anglo-German friendship agreement with Hitler. Chamberlain returned to London apparently convinced that appeasement had satisfied Germany.
In March 1939 Germany invaded Czechoslovakia; the policy of appeasement had failed terribly. Germany seized the city of Memel from Lithuania, and Italy invaded Albania in April 1939. Hitler applied pressure to the Polish Government and strengthened the Italian alliance through the Pact of Steel in May. The situation was now grave.
The Franco-Polish Treaty of Mutual Assistance stated that France and Poland defend each other in the event of unprovoked aggression. Britain and France pledged to defend Poland, and the Anglo-Polish Treaty was signed on 26 August 1939. Hitler secured a non-aggression pact with USSR on 23 August. Despite this, only one week later on 1 September, Germany invaded Poland. On 3 September 1939 Britain and France declared war on Germany.