You can say that the cannon is a kind of giant revolver: inside it, a metal piece (the hammer) hits an ammunition filled with power, causing an explosion that spits a projectile towards the target.
The working principle of this indispensable weapon in the arsenals of armies has remained more or less the same since its appearance in the 13th century, when Europeans discovered gunpowder.
Since than, cannons have already decided several wars and they continue to do so as more modern models are used by all the armed forces in the world.
Come and learn how Portuguese soldiers in 17th century loaded and fired a cannon at Forte S. Jorge Oitavos, Cascais, Portugal.