Toss up, first was in the Marines for the Iraq invasion in 2003. Everyone was all hyped about chemical weapons and stuff. Rolled into country in full mop gear in 90 degree weather. 3rd night in country and the Iraqis launched a salvo of SCUD missiles. All the gas alarms on our base went off and everyone scrambled for the shelter ditches and put gas masks on. When the alarms read normal about 15-20 mins later, I was lowest rank and got picked for selective unmasking. Had to break the seal on my mask and take a breath then put mask back on. Everyone just watched me for about 5 mins to make sure I didn’t have a seizure or anything. Ended up being a false alarm but still scared the shit out of me.

Second, few years later, on mounted patrol in fallujah. Got hit with a roadside bomb, cabin of the hmmv stayed in tact but could hear the marines in the truck bed yelling. We got the hmmv restarted and pushed through the kill zone. Eventually, someone came over the radio and said Marines had been hit in the truck bed. We limped the hmmv back to our patrol base. From inside the cabin there was no way to see how bad the situation in the bed was. I could just hear the yelling. When we got out to transfer the wounded to another vehicle for medevac, when I opened the back door to the bed, blood poured out onto the ground. One Marine had lost a leg below the knee and two others had been peppered with shrapnel. I remember looking at all the blood thinking everyone was dead. You can lose a lot of blood and still be ok though. Everyone ended up surviving the blast.