Whats a Boss Battle?

[Ironhawk]

I also just won the Boss Battle.
Open journal and click on the task to get the black pearl.
Two button appear on the journal.
"Fight Boss Battle now" and "Look for Boss Battle"
Click on the Battle now and it will take us to a cutscene
where we offer paper to two dumb navy guards and then
we steal a frigate(?). Then we are taken to a new scene where
we are on the ship ready to steer it. At this point there are four stages:
1. Steer the ship toward the three Navy light frigates
2. Use our cannon to sink one of the ship. The other two
seem to be automatically sunk, and i couldn't use broadside
to sink them as it won't let me take the wheel during this stage.
3. After all three ships sunk, destroy the drawbridges that block
your way. There are 5 bridges but we only have to destroy 4 as
bridge 1 and 2 are connected. We can use canon or broadside
to destroy them. Took about 50+ round canon or 20+ broadside to
destroy one side of the bridge each, so it's rather boring.
And the canon from the fort don't damage our ship so ignore them.
4. Last one is the Navy Goliath (lvl 38 War frigate). I couldn't use
broadside or canon to attack this ship, only Ramming Speed can
damage it. Took 7 ram to bring her down, and the Goliath's canon
also didn't do any damage to my ship.
Too easy i think, unless the fort's canon and Goliath can make
any damage to our ship then we might need to crew up to win
this Boss Battle.