Drawing the line between combatant and innocent civilian in war

[Pavement Pounder]

Where do we draw the line between combatants that are fair game and 'innocents', between military and civilian targets? Especially in this era of total war, and when the populace is directly involved in the war effort? People who have no say in military matters should not have to suffer a war they did not want, yet are those who actively support the military 'guiltless', or rather, exempt from attack?