Friendly fire happens. It's tragic, but there's no use obsessing over it. That's war.
In WWII, there lots of incidents of friendly fire. 200 men were killed in Normandy, including their general, when a bombing mission aimed short. If we had stopped to investigate and tried to consider every conspiracy angle, we'd have never had time to get to Berlin.
Tillman was famous, so they decided to cover up their mistakes. Yes, friendly fire does happen. It's probably "what" happened.
But it's still the cover up, "stupid."
Was this the break-out at St. Lo? If so, it's remarkable that it wasn't thousands. 1,800 B-17's and 900 B-26's -- a formation 80 miles long -- bombed the German lines. They didn't fly parallel but perpendicular to the front lines. Not a "mistake" per se but because the AAF theorized it would take too long to get the bombs on target flying parallel which would give a lot of the Germans time to escape.