The Viking women under Lagertha attacking the bridge by swimming under cover of darkness and then producing bows to kill the defenders makes great TV but is complete nonsense. Throughout Dark Ages and medieval history, the bow was notorious as being a poor weapon when wet, even by light rain. The gut, sinew and wood used in their construction were prone to damp, while the glue which held it all together would quickly disintegrate in the presence of water. The historical records are full of stories where this sort of problem changed the course of battles. Even in light rain, archers would unstring their bows and wrap them in oiled leather to keep them dry, and archers would often be all but useless on the battlefield in adverse weather.
