The Army’s organizational expression of versatility is the modular brigade. From an Army that was organized to optimize division operations, we have reorganized to optimize brigade operations. The modular brigade is decentralized, combined arms and enabled. While we are continually reassessing its design based on lessons learned, we are confident that it provides us a full spectrum capability—the ability to conduct offense, defense and stability operations—against current and emerging threats.
Not that we should ridicule the old divisions that could reach nearly 20,000 in manpower. They served their purpose. Remember, they were big and clunky, but they had a very specifice purpose that the full spectrum capability of the modern self-contained brigade (of about 3-4,000) probably couldn't handle.
Those old divisions needed to be robust enough to absorb multiple waves of Soviet heavy armor in West Germany and still stand at the end of the day to keep the Russians from the Rhine. At one point, our objective was to build a division with a thousand organic anti-tank weapons--cannons and missile launchers--to attrite the frontal assault by the Red Army. We needed big. Our heavy division was big. To be fair, this division optimized to holding on the defense and waging a war of attrition was capable of switching to offensive warfare at the end of a longer supply line in 1991.
But let's have a little respect for the old division even as we celebrate the mobility and flexibility of the new brigade combat teams. The big 1980s division served its purpose in the Cold War only to be replaced by the mobile organization of the modular brigade we have now, just as the square division of World War I suited to attrition was replaced by regimental combat team/combat command organized triangular divisions in World War II suitable for mobile warfare.