How has war changed over the years?
War has changed. Its no longer about nations or idealoligies or ethnicity. Its an endless series of proxy battles fought by mercenaries and machines. War and its compsumtion of life has become a well oiled machine. war has changed. ID tagged soldiers carry ID tagged weapons, use ID tagged gear. Nanomachines inside their bodies enhance and regulate their abilities. genetic control. information control.emotion control. Battlefield control. Everything is monitored and kept under control. War has changed. The age of deterrence has become the age of control. All in the name of averting catastrophe from weapons of mass destruction. And he who controls the battlefield... controls history. War has changed. when the battlefield is under total control... war becomes routine.
Different answer: War was routine when it was fought with rocks every season by the same tribes. Technology changes, levels and capacity change, but basic tactical, logistical, and strategic issues never change. The Iraqis face the same problems against US tanks and bulletproof armor that Germanic tribes faced against heavily armored and organized Roman legions. The actual issues of engineering change, but the difficulties, how to defeat an enemy you can't directly harm in a stand-up fight, how to utilize or adjust weapons incapable of dealing lethal blows against enemy armor in a single strike, how to organize a system of traps to disrupt the supply lines of a force you can't confront directly.
Another example would be international arms races, arms regulation, and cold wars. The first recorded cold war was between the Sumerians and the Elamites 6,000 years ago. They utilized proxy forces, shifting alliances, arms races, and political maneuvering in much the same way as the US and USSR until Sumeria annihlated Elam in one quick war after several hundred years. The pope banned the crossbow in the tenth century. He believed it killed people so brutally, so efficiently, that no society could survive incorporating it into a war, and it would mean the end of Christendom (and indeed the crossbow has killed many times more people than the nuclear bomb, which I compare it to in terms of it's initial tactical value). Crossbow units for years did not fight but simply marched onto or near battlefields to get the enemy to leave, or faced off with other crossbow units without violence.