From Benét's Reader's Encyclopedia:

"The author of works of theatrical criticism , Sastre emphasizes the didactic function of drama . Most of his plays — which frequently went unproduced in his own country for many years under Franco - involve solitary protagonists , in conflict with an absurd world of false values , who end in failure . In such plays as Escuadra hacia la muerte ( 1953 ; tr The Condemned Squad , 1961 ) , La mordaza ( 1954 ) , and Guillermo Tell tiene los ojos tristes ( 1955 ; tr Sad Are the Eyes of William Tell , 1970 ) , he pleads for justice and individual liberty while pondering the moral ambiguities involved in modern life . Crónicas romanas ( Roman Satan 868 Chronicles , 1968 ) represents a turn to the EPIC THEATRE in the Brechtian mold."

https://www.elmundo.es/cultura/literatura/2021/09/17/6144629521efa0e44d8b463f.html
(in Spanish)

https://www.abc.es/cultura/abci-muere-95-anos-alfonso-sastre-grandes-dramaturgos-teatro-posguerra-202109171136_noticia.html
(in Spanish)

https://thecanadian.news/2021/09/17/playwright-and-essayist-alfonso-sastre-dies-at-95/

The Madrid playwright and essayist Alfonso Sastre, National Theater Award winner in 1986, died this Friday at the age of 95 in the Guipuzcoan town of Hondarribia. The also film scriptwriter was one of the main exponents of the so-called Generation of 50. His personal career has been characterized by his political and social commitment and the denunciation of the Franco regime until the end of the dictatorship. From the beginning of the 1970s he participated in a significant way in support of the Basque nationalist left.

“Farewell to a theater revolutionary. The playwright Alfonso Sastre, a renovator of contemporary theater, has passed away. His unwavering political commitment was a constant in his career. Our condolences to those close to him”, has highlighted the General Society of Authors and Editors in its twitter account.