This remains controversial. It may not have been overtly political but more personal. It may also have had something to do with Lorca being a homosexual.
Yes he was writing things that weren't against them but also he wasn't a nationalistic poet so he wasn't on their side and if he wasn't it was enough reason to execute him that time.
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In July 1936, ignoring his friends' warnings and turning aside travel offers to Colombia and
Mexico, Lorca left Madrid to spend the summer in Granada. A political crisis was already
engulfing the Second Republic. Two days after the poet traveled to Andalucía, the
Spanish Civil War broke out, occasioned by the revolt in Spanish Morocco of an army
garrison under General Francisco Franco. Within two days, the Granada garrison
followed suit, the first army installation on the Iberian mainland to join the coup. Two
weeks later, Lorca's brother-in-law, the mayor of Granada, was arrested by the Fascists.
After a fortnight in custody, he was executed. The same day, August 16, Lorca himself
was arrested. He had already been threatened by armed thugs at the family farm and
gone into hiding in Granada with a friend whose family was influential in the Falange.
Lorca was confined for several days, then taken out with another man, a one-legged
schoolteacher from a nearby village, and shot. They were buried in an unmarked grave in
a grove of olive trees.
Why was García Lorca executed? No one is completely certain. However, his family was
known locally as sympathizers and supporters of the leftist Popular Front and as friends
with the liberal Fernando de los Ríos. The poet himself was decidedly antifascist, with a
viewpoint that was drifting leftward and writings that showed an increasing focus on
social issues. He commonly answered questions about his political affiliation by saying, "I
am on the side of the poor." But Lorca had a true artist's hatred of politics and parties. "I
will never be political," he said only a month before his death. "I am a revolutionary
because there are no true poets that are not revolutionaries. Don't you agree? But
political, I will never, never be!" The Fascists, on the other hand, were truly political.
They were embarked on a wave of sectarian violence, a social purge, that would kill
some 4500 citizens of Granada alone in the next four years.
"I want to sleep awhile, / awhile, a minute, a century," Lorca wrote in "Gacela of Dark
Death" soon before his actual death, "but all must know that I have not died."
What did not die or disappear was his voice -- "there is a stable of gold in my lips," he
wrote in "Gacela of Dark Death" -- and a vision of a modern theatre for a modern Spain
at the time when Spain itself retreated into a dark age.
The crime was in Granada.
This remains controversial. It may not have been overtly political but more personal. It may also have had something to do with Lorca being a homosexual.
Yes he was writing things that weren't against them but also he wasn't a nationalistic poet so he wasn't on their side and if he wasn't it was enough reason to execute him that time.