The scope of the fighting in Iraq and Afghanistan can be seen in the number of medals awarded. Over half a million U.S. Army personnel have served in Iraq and Afghanistan since September 11, 2001. U.S. Army troops have received 11,900 medals for valorous acts ("above and beyond the call of duty") in combat. These comprised (in order of merit); two Medals of Honor, 19 Distinguished Service Crosses, 542 Silver Stars, 192 Distinguished Flying Crosses, 3,103 Bronze Stars for Valor, 1,273 Air Medal For Valor, and 6,769 Army Commendation Medal For Valor.
There were also 126 Soldiers Medals awarded for valor that did not involve combat. For example, if a soldier ran into a burning building to save other, that would rate a Soldiers Medal. There were also 22,975 Purple Hearts awarded to any soldier who was killed or wounded in action.
There were 52,505 Combat Infantry Badges, 14,018 Combat Medical Badges, 68,511 Combat Action Badges awarded to soldiers who had experienced combat. The Combat Infantry Badge is only awarded to the ten percent of the troops sent overseas who are infantry, while the Combat Medical Badge only goes to those with medical jobs (usually medics in combat units). The Combat Action Badges (CAB) is awarded to troops who are not infantry or medical personnel, who have been in one recorded incident of combat with two witnesses.
The CAB has an interesting background. For the last century, the infantry have suffered most of the casualties (about 80 percent.) But that has been slowly changing. In Iraq, the infantry have taken less than half the casualties. And many artillery and armor units have been temporarily reassigned (after some refresher training) to infantry duties (mainly patrolling.) This is nothing new. During World War II, tanks often served with infantry units. When a tank got hit, most of the crew usually survived, and got out of the vehicle uninjured. They were then expected to "fight as infantry", at least until a new tank was available for them or their damaged tank was repaired. Artillerymen keep their infantry skills up to date, and regularly set up defensive positions when they are in the field. Artillery units sometimes got hit by enemy infantry, or enemy artillery. Despite all this, these other combat troops have never been eligible for the CIB. The CAB was introduced four years ago, for these troops, and the thousands of military police (who run convoy escort duty), EOD (bomb disposal) and support troops of all types who are now getting shot at and exposed to roadside bombs.
Some awards for valor also have versions for extraordinary achievement in the combat zone that does not involve combat. Thus there were awarded 99,583 Bronze Stars and 292,272 Army Commendation Medal for achievement. This would be for things like months of 12-16 hour shifts in a maintenance, medical or supply facility, or simply doing an outstanding job.
Overall, the army has awarded 651,805 medals for the troops who have served in Iraq and Afghanistan, meaning that most troops who served there got at least one. About a third of the troops in Iraq and Afghanistan are from the marines (for the most part) navy and air force. The marines give out far fewer awards than the army, and always have. The air force and navy also adopted a combat badge for their personnel who came under fire while working with the army and marines.
These awards go back to antiquity, as a way to recognizing extraordinary performance in combat. Back then, the medals, ribbons or whatever often included money or goods as part of the reward. The ancient Romans had a long list of military awards, both for combat and non-combat performance. Napoleon Bonaparte is credited for reintroducing the awards in the modern period, as a means of motivating his troops to heroic deeds.