fm 31 21 guerilla warfare and special fm 31 21 1961 guerilla warfare and pdf american guerrilla warfare cal u s army special forces unconventional guerilla warfare and special forces restricted u s army special operations us army field manual 1961 training u s army special forces unconventional war books building a counterinsurgency psychological operations in guerrilla 1958 1961 1965 1969 guerilla warfare bashing guerrilla warfare manual the german army guerrilla warfare pocket manual 1939 45 book irregular warfare doctrine fm 31 21 1969 special forces operations a guerrilla warfare manual for everyone u s army special forces handbook