Possessive apostrophes are used when someone owns something or when all of the people own it. You will not need an apostrophe  in the following sentence because there are lots of Vikings. The Vikings charged to the side of the ship.

So now I will show you when to use an apostrophe in a sentence where a person owns something. The Viking’s bow and arrow is used for shooting enemies.

Now I will show you how to use an apostrophe in a sentence  when all of the people own something. All the Vikings’ ships have a figure head to scare their enemies .

So that is how you use possessive apostrophes.

Saad