a second life of service

1945
the war has ended not much differently from our own timeline but some things didn't happen.
Japan
The IJN Yamato and Musashi are still afloat and being sailed to america for testing.
Britain
The HMS Hood survived her encounter with the Bismarck thanks to the valiant sacrifice of the Prince of Wales and her crew.
Australia
The famous WW1 era destroyers of the Australian scrap iron flotilla have survived the entire war and have become museum ships.
America
The USS Arizona returns home after being present at the official Japanese surrender alongside the state-of-the-art Iowa class battleship USS Missouri.

2015
Seventy years after the end of WW2 these old warships and more have been repaired and made ready to put to sea for a worldwide showcase to celebrate the end of the war.
The modern warships of the world are sitting in their naval bases ready to participate in the showcase.
But danger lurks beyond the horizon.
A mysterious fleet sits hidden, ready to launch their crippling attack before attempting to rule the seas.
How will we fight back against this unknown enemy?
Will we succeed?
Or will we be lost forever.