From an officer in the U. S. Army:

In WW II, our first aim was to conquer the Axis….When you conquer a people, then you must use overwhelming force to impose your will and to secure the place. Later, you ease up as the populace gets used to free markets, rule of law etc.
When we convinced ourselves that we would be greeted by the Iraqi people, we viewed our mission as one of liberation and not conquest and so, got off on the wrong foot. One major misjudgment was that we would be able to occupy the place with fewer than 200,000 troops. These forces aren’t enough to impose our will. While we are too strong to be chased out of the country, we aren’t strong enough to cow would-be attackers into staying out of our way.
To illustrate how it should be done: One weekend in July 1945, 500,000 U.S. troops conducted a house-to-house search in the Frankfurt area and arrested about 80,000 Germans (mostly veterans I think) who violated the Allies’ weapons laws. We were able to use that much manpower because we still had millions of troops in Germany. By conducting operations of this magnitude, we were able to establish control of the situation despite the fact we were shipping troops out of Germany by the thousands each month.
Hi-tech may be a gee-whiz way to win wars rapidly but when it comes to occupation, God still favors the big battalions.