The reason 1300 Palestinians were killed was because the terrorist government (Hamas) they elected chose to fire thousands of explosive rockets at Israeli population centers. (One rocket would, as an act of war, have justified Israel's response.) The reason a third of them were children was because the same terrorists, in direct contravention of the Hague and Geneva Conventions, used them and other civilians as human shields; a war crime punishable by death if civilians die as a result. The reason that "only" 13 Israelis died was not for want of effort on the part of the terrorists, and the fact that an aggressor shoots at you repeatedly and misses repeatedly does not mean you are not within your rights to shoot back and kill him.