Marino remained neutral and Italy adopted a hostile view of Sammarinese neutrality, suspecting that San Marino could harbor Austrian spies who could be given access to its new radiotelegraph station. Italy tried to forcibly establish a detachment of Carabinieri in the Republic and then cut the Republic's telephone lines when it did not comply. Two groups of ten volunteers did, however, join Italian forces in the fighting on the Italian front, the first as combatants and the second as a Medical Corps operating a Red Cross field hospital. The existence of this hospital later caused Austria-Hungary to suspend diplomatic relations with San Marino.
From 1923 to 1943, San Marino was under the rule of the Sammarinese Fascist Party (PFS).
During World War II, San Marino remained neutral, although it was wrongly reported that it declared war on the United Kingdom on 17 September 1940.
Three days after the fall of Benito Mussolini in Italy, PFS rule collapsed and the new government declared neutrality in the conflict. The Fascists regained power on 1 April 1944 but kept neutrality intact. Despite that, on 26 June 1944 San Marino was bombed by the Royal Air Force, which mistakenly believed that the country had been overrun by German forces and was being used to amass stores and ammunition. At least 35 people were killed in the operation. San Marino accepted thousands of civilian refugees when Allied forces went over the Gothic Line. In September 1944, it was briefly occupied by German forces, who were attacked by Allied forces in the Battle of San Marino. Allied troops withdrew from the country shortly afterwards.
San Marino had the world's first democratically elected communist government, which held office between 1945 and 1957.
San Marino is the world's smallest republic, although when Nauru gained independence in 1968 it challenged that claim, Nauru's land mass being only 21 km (8.1 sq mi). However Nauru's jurisdiction over its
