On the event info page is stated following:

"7. Limited Time Offer! For every 10,000 olives spent during event period, you can request to lock 2 of your crew under level 54(Max 53)stay at the level forever. (Every account can only lock up to 4 sailors. This will be different from the Blitzkrieg sailor that will be released in July as Blitzkrieg sailors will be 13 base in stats,so if you want lock better sailors to play Blitzkrieg forever, this is the chance)"

So where to find or how to get that Blitzkrieg-Sailor supposed to have been released in July?