Warfare As with present-day radar, nuclear energy and penicillin, warfare has always accelerated the development of new products, processes and equipment. Necessity, indeed, is the mother of invention! And that thought necessary often brings conflict! The search for new hunting or grazing grounds no doubt brought the earliest confrontations between early man, prompting the development of hand weapons. However, the growth of the cities, trade and accumulated wealth spawned ever larger groups of raiders, then armies, to besiege these major sites of booty and potential slaves. Threats to urban occupants on an ever-increasing scale brought a change in the nature of lifting. As life was threatened, as well as possessions, the elevating of earth, timber and stone to construct city walls was often frantic, requiring the mobilization of inhabitants. In many instances, more material went into the fortifications encircling a town than in the inhabitants' housing! On a more expansive scale, some 300,000 laborers spent 800 years lifting earth, stone and brick in constructing the 1,500-mile-long Great Wall of China (25 feet high, 20 feet wide at the botom and 12 feet at the top), designed to protect the northern and northeastern portion of the country from Mongol incursions. Historically, the pendulum has always swung between defense and offense. The higher the walls, the greater the ingeniousness given to breaking them down. Catapults hurled projectiles against the walls, and multistory towers carrying attackers, were designed to be rolled against the walls. One graphic depicts a portable tower equipped with a rude lift to elevate attackers! Towers added to the utility of the city walls and finally, as in Italy, families or clans within cities constructed towers to scan the surroundings and protect the premises. Castles that dotted the European countryside were literally a huge conglomeration of towers, walls and turrets -- a fortress -- designed to discourage or repel enemies.