, or its chemical name dibenz[ b , f ][1,4]oxazepine, is an incapacitating agent and a lachrymatory agent . CR was developed by the British Ministry of Defence as a riot control agent in the late 1950s and early 1960s. Read more... Edit at Wikipedia... Other names Dibenzo[b,f][1,4]oxazepine (IUPAC Name); dibenz(b,f)(1,4)oxazepine References Please