You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Valencia

Context:
The vicereine Germaine of Foix brutally repressed the uprising and its leaders, and this accelerated the authoritarian centralisation of the government of Charles I. Queen Germaine favoured harsh treatment of the agermanats. She is thought to have signed the death warrants of 100 former rebels personally, and sources indicate that as many as 800 executions may have occurred. The agermanats are comparable to the comuneros of neighbouring Castile, who fought a similar revolt against Charles from 1520–1522.

Question:
Whom did the comuneros rebel against?

Charles