Playing League campaign sub hunt - need some tips cause I keep on losing...

I worked this mission around the flagship carrier and basically just tried to keep ships moving that way if they could make it, or damaging/stalling subs if they were definitely outmatched. Also remember you can leave adjacent hexes open around your carrier, you just need a donut of ships or land at the 2hex range so the subs can't hit. Oh and with any ships that are clearly lost, you should fire for maximum damage rather than maximum kills (IE don't fire shots that result in negatives because your carrier will have no trouble dispatching the wounded subs as they come in range). Maybe not the best way to do it or anything but it worked for me well enough.

here is how i've beat the subs

the main thing was to move my ptero to the island beach
this greatly reduced possible attack points - the subs can't attack from the ground
(the position was not the best, but it worked)

other thing is to move the large group of killerwhales (those ones which are not attacked at first round) to the fortified fleet

i've started to move the carrier only when i've devastated all nearby subs
many of my shielding killerwhales vanished too and only option was to run away

at the end i had nearly dead ptero and two killerwhales