What @Deophaun said. They weren't all in the same tent, they were scattered around in lots of various different tents or left open on the quartermaster's desk or dipped in perfume to smell like it came from a lady. There were lots of different methods of delivery. A couple of them were slipped in to pants pockets of uniforms so that when they were found later they would be read and explode. Since it's a small piece of parchment, there was never any evidence of where the explosions were coming from.