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:
John_Kerry

Context:
Kerry was arrested on May 30, 1971, during a VVAW march to honor American POWs held captive by North Vietnam. The march was planned as a multi-day event from Concord to Boston, and while in Lexington, participants tried to camp on the village green. At 2:30 a.m., local and state police arrested 441 demonstrators, including Kerry, for trespassing. All were given the Miranda Warning and were hauled away on school buses to spend the night at the Lexington Public Works Garage. Kerry and the other protesters later paid a $5 fine, and were released. The mass arrests caused a community backlash and ended up giving positive coverage to the VVAW.

Question:
Why were the protesters arrested?

tried to camp on the village green