Non pas vraiment Bahamutzero84 tu a tout faux.......

During this war, Akainu contacted Squad, and told him that Whitebeard and Sengoku made a deal, that they won't kill Ace and the Whitebeard pirates in exchange for wiping out the New World pirates. (meaning, to offer them as sacrifice of war)
Squad's pirate crew was wiped out in the past by Roger.
Marines knew that, and that's why they contacted Squad, thinking that they'll be able to use him for their scheme.
Sengoku most likely revealed about Ace being Roger's son publically for this intent. 