Spanish civil war
In July of 1936, Spanish generals, led by Francisco Franco attempted a coup to take over the government after the unrest in Spain after the elections of 1936. The coup was not complete, with many of the major cities' militias stopping it. The Nationalists, as the rebels became called, began a series of attacks in Spain and in Northern Africa, defeating the Republicans again and again. Germany and Italy airlifted over 50,000 troops into Spain, making it the first large-scale airdrop ever. France and Britain, not wanting German power to increase any further, sent their own troops and supplies into Spain, turning the tide of the war in the Republicans favor. The army led by Franco in Africa had seemed invincible until British and French troops virtually destroyed it in the battle of Gibraltar, causing the Nationalists to lose hope in their cause and to fight only minorly from then on. Spain then entered a brief but deadly war against Portugal, switching their government to support the Spanish government and the Entente Powers.
Spain entered World War Two after Germany invaded France. Seeing their ally falling before the far superior German military and worried about protecting their own borders, Spain tentatively declared war on Germany but not any of the other Axis powers, trying to seem like a small, unimportant nation that would only affect the war minorly. In Late 1940, German U-boats sunk many Spanish passenger carriers, saying that the ships had held weapons and bombs. Spain responded by sending 500,000 troops (around 30 divisions) to France to help the falling French and British resistance. More troops followed, and the Axis advance slowed down. The French almost had held the Germans back when the Alsace-Lorraine front finally broke through the weak point in the Maginot line.