A belfry was a two or three storey wooden building covered with green hides as anti-fire precaution. This building would be pulled along a level path to the castle wall and hopefully be tall enough for men to walk over the wall. If the belfry was too tall, archers would shoot people while they lower a drawbridge to use. The idea behind this building was that attackers should be on equal levels with the defenders. Rams were even sometimes used underneath the belfry. The main disadvantages were that they were clumsy, slow, and the men propelling it were subjected to intense fire.
Breaching weapons were used for close range attacks on walls. They first needed a protective cover so a stout rectangular framework known as a tortoise, penthouse, rat, sow, or cat was used. The defenders of the castle would drop rocks, pour boiling water or oil, and attempt to set the cat on fire. While the cat would protect the men a ram or bosson would be used under the cat. A ram was a huge baulk of timber chained to the top of a cat and up to sixty men would propel it against the wall. The ram also had a metal end to help break the wall up. The defenders of the castle would then lower large mattresses to protect the wall or lower beams in order to lift the ram and make it ineffective.
A trebuchet was a powerful and accurate stone-throwing machine. It consisted of a frame with a crossbar on which was pivoted a long arm. It had a short end which held a container to fill with weights and a long end which bore a sling. It was used to throw rocks and sometimes corpes of horses in hopes of spreading disease. The men who manned the trebuchet were prime targets of archers on the walls.
In the begining canons were made out of wrought iron. They would use iron balls but the cost and weight of them led to the usage of stone balls. Stone balls began to be used in larger canons and since they were lighter they required a small charge of powder. These stone balls were less effective though because sometimes they would shatter when hit against a fortification. Yet when the stone balls were shot over the walls they became effective at hitting people on the other side if they shattered. Gunpowder for the canons were mixed on the spot so it would not explode while traveling. A good advantage of the canons was that their range was farther than the longbow but since it was hard to transport they were sometimes not used.