During the 15th century, artillery crossed a threshold in gunpowder technology from the big bombards. Bombards were developed to beat at castle walls, and the French artillery took that basic function and improved upon it - considerably.
Bombards were usually constructed of iron staves held together with iron hoops, similar to storage barrels. If that does not seem sufficiently sturdy - they weren't. Bombards too frequently burst when fired, spraying shrapnel into their handlers.
This little bombard appears
to anticipate the
They were fat and made ungainly by being mounted in wooden trays with (at best) little wooden wheels to move them. Moving them was usually by oxen which was so slow, or by boat, wherever the attack point could be reached by navigatable water. Their crews were poorly trained and perhaps ill at ease around potential grenades. Bombards fired carved stone spheres, which required time and extra labor to hammer out the projectiles. The noise of bombards sometimes frightened defenders more than the effect of hurled stone spheres.