[3] Monzón was one of the founders of the Navarre branch of the Partido Comunista Español (PCE, Spanish Communist Party).

[1] In June 1935 he organized a major strike of construction workers in cooperation with the Carlist unions, where he showed strong leadership and the ability to work with people of different ideologies.

[2] The Popular Front triumphed nationally, but in Navarre Rafael Aizpún's Unión Navarra of the Bloque de Derechas (Right Block) took 70% of the votes.

On 5 March 1939 Negrín issued a decree appointing Monzón to take charge of the general secretariat of the Ministry of Defense.

[1] The PCE leadership left France after the Molotov–Ribbentrop Pact between Russia and Germany in August 1939 just before the outbreak of World War II.

[1] Monzón worked with Gabriel León Trilla in reorganizing the PCE members and placing them in the French Resistance.

[9] By the summer of 1944 the AGE veterans of the Spanish Republic's Popular Army had made a significant contribution to defeating the Germans in the south of France.

[11] In August 1941 the PCE in France started to form the Unión Nacional Española (UNE, Spanish National Union), which would unite all left-wing political sectors opposed to Francoism.

In September 1942 the Central Committee of the PCE in France offered to join with all anti-fascists including Carlists, Monarchists and the Christian Right.

[14] That month he established the Junta Suprema de Unión Nacional (Supreme Council of National Union) in Madrid, which was more wishful thinking than reality.

[16] The Val d'Aran was chosen for the attempt because it was on the north side of the Pyrenees and isolated from the rest of the country in winter.

[17] In his memoirs Santiago Carrillo cast grave doubts on Monzón's ability or motives in launching the invasion.

He said the PCE had told the Spanish communists in France not to attempt any mass invasion, but to infiltrate in small groups and settle inland.

Carrillo was sent to France, and learned from the leaders of the invasion in the Val d'Aran, which they said had been ordered by a "Supreme Council of National Union".

Carrillo said he managed to persuade the French PCE to abandon the project, since ten thousand picked militants would have been massacred by José Moscardó Ituarte, who had 50,000 troops.