“All armies have expendable items. That is, a part or unit, the destruction of which will not be fatal to the whole. In some ordeals, a man might consider his finger expendable, but not his hand; or, in extremity, his arm but not his heart. There are expendable items which may be lost or destroyed in the field, either in peace or in war, without their owner being required to replace them. A rifle is so expendable or a cartridge belt. So are men.
Men are the most expendable of all.”
Helmet for my Pillow, Robert Leckie, p. 96