I'll never forget the first time I did a 'window breach' on exercise. I was the first man in. We ran across the open ground in front of the building threw up the scaling ladder and I was up it like a whippet down a rabbit hole (I was a lot younger then, now its more like a St. Bernard trying to squeeze through a cat flap!!!). Me and the guy a couple of rungs behind me in the ladder tossed a couple of training grenades into a pitch black room and after a pair of bangs I jumped into the room rifle at the ready trying to look as tacticool as fook.
Unfortunately those sneaky Gurkas who were playing the enemy has decided not to defend that room and instead had just filled it waste deep in barbed wire, which I had just jumped right into the middle off. So instead of looking cool I ended up looking like a fish in a net. Unfortunately the net was made of very old and rusty barbed wire. I remember it must have taken me an hour with a set of wire cutters to get free and it cut my combat trousers to ribbons, and put a couple of nasty tears in my smock (I couldn't have cared less about the issue trousers, but I was wearing a pretty expensive Arktis smock that I had bought myself so I was well pissed about that).
I spent the rest of the day in the medics waggon with a blanket wrapped around my waste drinking overly sweet tea. Once they had cleaned me up there were no major lacerations just a fist-full of superficial cuts and grazes, but when I finally cut myself free It looked like I was wearing red tights under my trousers where the blood had been running down my legs. The medic must have asked me at least 20 times if my tetanus shot was up-to-date, which will tell you something about the condition of the barbed wire.