Cannon fodder is an informal, derogatory term for combatants who are regarded or treated by government or military command as expendable in the face of enemy fire. The term is generally used in situations where combatants are forced to deliberately fight against hopeless odds (with the foreknowledge that they will suffer extremely high casualties) in an effort to achieve a strategic goal; an example is the trench warfare of World War I. The term may also be used (somewhat pejoratively) to differentiate infantry from other forces (such as artillery troops, air force or the navy), or to distinguish expendable low-grade or inexperienced combatants from more militarily valuable veterans.