A West Yorkshire school has been forced to close for the day after 500 pupils walked out of lessons.
The protesters received a mixed reaction from local residents
Up to one third of the students at Ilkley Grammar School took part in a demonstration against impeding military action against Iraq.
Teachers were unable to prevent the morning walk-out and the decision was taken to close the school.
One protester said: "We want the town to know that Ilkley Grammar School is against the war."
Head teacher Mrs Gillian James was unavailable for comment.
The protest was one of a string around Yorkshire which coincided with similar protests by pupils around the country.
Up to 200 students gathered in Centenary Square in Bradford while smaller demonstrations also took place in Leeds city centre and Horsforth.
Another demonstrator insisted pupils were not simply using the Gulf conflict as reason to leave school for the day.
"There is a very strong feeling that people need to do something to stop this war starting with direct action," he said.
"This is teenage rebellion being harnessed to make a political statement."
Calder High School, in Halifax, has suspended 13 pupils following demonstrations on Tuesday.