Some good answers to your question from 3 years ago: https://www.reddit.com/r/AskHistorians/comments/1qlftd/how_did_vikings_protect_themselves_from_the/

edit: should have mentioned this was posted by /u/wee_little_puppetman

Do you have the source for the image? Knowing when it was made and by who could provide insight into how realistic it is.

Hello honored users!

This thread is on the rise and so far it has seen only answers based on speculation, joke answers ("they prayed to Thor") and answers that do not fulfill the standard of being in-depth, comprehensive, and informative as per our rules

So please, answer only when you can answer in line with our rules.

Otherwise, there might be a send off to Valhalla for you.