We know that Kaido “the king of beasts”, one of the four yonkou tried to cross Whitebeard’s path for a battle but was stopped in between by other yonkou “Red Haired” Shanks, due to which kaido was unable to reach Whitebeard. Although it is still unknown what exactly did happen between Red Hair and Hundred beast but Why exactly would Kaido attack Whitebeard , a strong foe which can be deadly.
I think that reason why kaido tried to attack on whitebeard was that Whitebeard either actually possessed or had information related to the last Road Poneglyph , Kaido knew that Whitebeard is going in a dangerous war so the chances of him survivng this incident were slim that is why he tried to get his hands on information from Whitebeard in a vulnerable situation.
He might’ve planned to stop whitebeard in his path and demand the information about the last road poneglyph, he might’ve done that because he knew how much Whitebeard loved his crewmates and Whitebeard was in hurry to save ace and if he himself would block Whitebeard’s path then Whitebeard would have no choice but to give him the information about that poneglyph, so that Whitebeard may go to marineford without any damages and reach there on time.
Kaido’s plan came to an end when he met Red haired shanks who shared same thoughts of crossing the path of another yonkou like him but he chose Kaido instead. We can say that Shanks might’ve stopped kaido so that Whitebeard may save Ace on time otherwise Whitebeard would be facing difficulty in reaching marineford on time.
On seeing Red Hair Pirates on his way, Kaido might’ve warned Red Hair not to mess with his business but as if Shanks might’ve cared about that. Now similar to whitebeard Shanks might know the position of the last Road Poneglyph (just a possibility) but opposite to whitebeard Shanks wasn’t in hurry and was ready to go on a full scale war with Kaido, and Kaido couldn’t take Shanks’s advantage like he could have done with whitebeard so he decided not to fight Shanks and pull back quietly ( It is to be noted that Shanks did not know about Ace being Roger’s son at that time. Otherwise I think he would have gone to marineford to save Ace himself with Whitebeard, with or without Whitebeard’s own agreement.)
Thank You for Reading .