Overcoming a moat around a medieval castle was a hard job.
In most cases, it meant almost certain losses in terms of men and in terms of time.
The attacking force first had to choose a viable method of attack.
If they faced a dry moat, this involved filling the moat with rocks, stones and wood thereby making it passable.
If they faced a wet moat, they had to either made use of makeshift bridges reaching the other side or make their way on floating barges.
In any case, the attackers had to proceed slowly and with caution in the face of attacks from castle walls.
During this time, there was also the danger of a reliving party arriving and attacking from the rear.