Fritz Hochwald (1897-1968) writes to Clarence. E. Holske of Munn, Liddy, Glaccum, and Kane, a New York-based law firm, regarding Hochwald's patent applications. At this time Hochwald is being detained at the Miranda de Ebro Concentration camp.

There were almost 200 concentration camps constructed throughout Spain by the national government of General Francisco Franco (1892-1975) to intern the Republican prisoners of war, both Spanish and international. Most housed Spanish nationals who had either supported the former Republican government in the Civil War or were thought to pose some sort of threat to Franco. Miranda, the largest, was built in 1937 to incarcerate the remnants of the International Brigade.

After the German army defeated France in June 1940, an avalanche of refugees headed to Spain, seeking safe haven from the Nazi persecutions. As it was increasingly difficult to obtain the documents to cross the border legally, many people resorted to crossing the border in secret. Although Spain was officially a neutral country, fugitives from France could not count on a benign treatment. On July 4, 1940, Spanish authorities decided to use Miranda de Ebro as an internment camp for the men of military age entering the country. Until its closure in 1947, a total of around 15,000 people were interned in this concentration camp. They were citizens of 67 different countries, mainly French, Canadian, British, Belgian and Polish.