Portugal and the Spanish Civil War
On the outbreak of the Spanish Civil War the Portuguese government of Antonio Salazar immediately supported the Nationalists in the struggle against the Popular Front government in Spain. Salazar feared that if the Republicans won the war his own authoritarian government would be under threat.
Salazar, concerned about the effect the events in Spain would have on his country, established a new militia that could serve as an auxiliary police. This new police force arrested dissidents and removed politically unreliable people from educational and governmental institutions.
Leaders of the Nationalist Army were allowed to negotiate with representatives from Nazi Germany in Portugal. After the signing of the Non-Intervention Agreement in September 1936, Salazar agreed that Germany could disguise the aid that it was giving by sending men, planes, tanks, and munitions via Lisbon. Salazar's police also arrested supporters of the Popular Front government living in Portugal. He also sealed off the Portuguese frontier to Republicans.
Although he came under considerable pressure from Britain and France, Salazar refused to allow international observers being stationed on the Portugal-Spain border. Officially he claimed that it would be a violation of Portugal sovereignty while in reality he did not want the world to know about the large amounts of military aid that was crossing into Spain.
Primary Sources
(1) The Manchester Guardian (28th September 1936)
Yesterday Senor Alvarez del Vayo, the Spanish Foreign Minister, sent to the Secretary General of the League documents containing the latest information in regard to alleged violations of the non-intervention agreement by Germany, Italy, and Portugal. It is understood that the documents contained detailed information of a grave nature.
I understand that so many airplanes have been supplied to the rebels by Germany and Italy that they now have about three times as many as the Spanish Government whereas at the beginning of the civil war the Spanish Government had about four times as many as the rebels. The rebels themselves are unable to manufacture airplanes, so that all these additional airplanes must have been supplied by other nations. German and Italian airmen who have been taken prisoner have confessed that they were acting under orders of their Governments.
The documents are understood to contain evidence showing that during the military operations of the rebels in Estremadura the air bases, the supplies, and the movements of the rebel troops were organized on Portuguese territory with the help of the Portuguese military forces. Airplanes and other arms that have fallen into the hands of the Government are of a type that has never existed in the Spanish army and reveal their foreign origin.
The Spanish Delegation asked that the documents should be published and should be distributed to the members of the League. They have not yet been distributed, and it is impossible to obtain from the Secretariat any information as to whether they will be published.