With what and with what area of Europe is the title Les Bonnets Rouges associated?

Answer 1

Tax protest, Brittany
Revolts in 1675 and in 2013 were staged in Brittany against tax proposals. The people in the 1675 revolts wore red bonnets or caps (or blue depending on the region); tax protests in 2013 which began in Brittany also harked back to the history and adopted the name.