As I've said before, military officers and NCOs in the US armed forces are required to attend and graduate various professional military education requirements throughout their careers. Over and over, officers and NCOs hear how battles were lost because the political leadership would not support going in with more troops. The incidents portrayed in "Blackhawk Down" were the result of the Clinton administration refusing to send in armor to support the ground forces. Vietnam holds multiple examples of civilian leaders in Washington D.C. selecting targets for the military in theater. The Bush Administration sent Marines into Iraq hundreds of kilometers beyond their doctrine and logistical lines could support (fortunately the Iraqi military did not present much resistance).
Now this report shows the British were sent in too light to handle Afghanistan. The results were high casualties.
Colin Powell believes you should only send in the military when all other options have been exhausted. Once you decide to send in the troops, you need to send them in so overwhelmingly that not only is victory assured but your enemy will regret ever resorting to war. Waging war on the cheap, or trying to minimize the presence of forces, only results in troops needless dying for no gain.