After two months in Paris as secretary to Ambassador Álvaro de Albornoz, Cernuda returned to a besieged Madrid, in September 1936. He took part in radio programs aimed at boosting the morale of the defenders of the Republic. In late November 1936, he enlisted briefly in the Alpine Battalion stationed in the Sierra de Guadarrama. In January, he returned to Madrid and moved to the building of the Alliance of Antifascist Writers and Artists. He published a statement in support of the Republic in El mono azul, the Alliance’s newsletter.
In April 1937, he moved to Valencia, where he contributed poems such as “Elegía a un poeta muerto (F.G. L.)” to the periodical Hora de España. In August, he played the role of Don Pedro in the staging of Federico García Lorca’s Mariana Pineda, a performance specially produced to coincide with the II International Congress of Antifascist Writers. The rehearsal helped the troupe (Manuel Altolaguirre Víctor María Cortezo, María del Carmen Antón, and María del Carmen García Lasgoity, among others) to forget for a while the horrors of war.
Cernuda spent the winter of 1937-1938 in Madrid, where he wrote the play El relojero o la familia ininterrumpida. Though reluctant to leave the country, he finally accepted the invitation of English poet, Stanley Richardson to give a series of lectures in British universities in February 1938. Cernuda thought that he would be away for a couple of months, but in fact, he was never able to return.