Morphine is the most important painkiller in World War II, on the battlefield, the armies of various countries are widely used, the United Kingdom is still poor, the U.S. Army medics can be directly on the front line for the wounded soldiers effectively injected with a controlled amount of morphine,
American Schweppes developed the Siret Morphine hypodermic syringe like a miniature toothpaste tube with 32 milligrams of morphine inside. The mouth of the tube is sealed, and a double-ended syringe is installed in front of it. When using it, the syringe is pressed down to break the seal, and then injected subcutaneously. The syringe is pinned to the casualty's collar after injection to allow the morphine dosage to be calculated and to prevent overdose: