A state of war exists when a country is attacked and has to defend itself, or if a country decides to attack another country, but in these modern times an attack occurs usually by surprise so no declaration of war usually occurs or it would give the game away, the element of surprise is predominant in strategy to create an advantage.
The military are supposed to attack valid military targets but recent wars have taken actions against civilians contrary to the Geneva Conventions. But is this an inevitable consequence of the huge reliance on rockets and bombs as primary weapons that have to be used to enable a ground force to attack without being ambushed?
War has rules which are flouted. These norms of behaviour appear to be a fragile set of conditions that if applied 100% give an attacker a disadvantage, or indeed a defender. The idea of a war being a confrontation between armies, well away from towns and cities only seems to play out in computer games and have nothing to do with modern military encounters. Clearly, there is an advantage to both sides in a war if the spoils of war are not spoiled by destruction. Rebuilding is also a source of economic activity and honour earning new alliances strength and purpose.
During times of peace, complacency rules, and friction builds. Eventually war erupts and chaos rules. Political solutions sought during times of peace sometimes take years of negotiation. Treaties are only as good as the mutual respect shown. War causes the erosion of civilisation. The rules of war do not seem to apply in these times. The rules of peace – what are they?