So if you're wondering why the sailors and the Winx started fighting it's because of their enemies to lazy to get rid of them thought that the best way to get rid of them was to spell them into thinking they were enemies.

The Trix and some other bad guys put a spell on then and then when they saw each other they started fighting. they thought it would be entertaining to see fairies destroying sailors.

When the enemies realized it didnt work they started fighting and arguing with each other and ended up destroying themselves and each other

The Winx found out about the ticks their enemies pulled and told the sailors. In the end they ended up becoming friends.