Young people must be given a true picture of Army life, not a "marketised version", the National Union of Teachers conference heard.
The Ministry of Defence (MoD) denies actively recruiting in schools but says it does visit to raise awareness when invited in by head teachers.
Some teachers complain the Army uses sophisticated methods of recruitment.
Paul McGarr, a teacher from east London, said only when recruiting materials gave a true picture of war would he welcome them into his school.
'Shoot and possibly torture'
These would have to say: "Join the Army and we will send you to carry out the imperialist occupation of other people's countries," Mr McGarr said.
"Join the Army and we will send you to bomb, shoot and possibly torture fellow human beings in other countries.
"Join the Army and we will send you probably poorly equipped into situations where people will try to shoot or kill you because you are occupying other people's countries.
"Join the Army, and if you survive and come home, possibly injured or mentally damaged, you and your family will be shabbily treated."
Hard to believe this is the same Britain of Marlborough, Nelson and Churchill.
