Michael tells him that he knows it was him, but what was it exactly that he did? What hit was he in on?

He knew Fredo was the traitor in his family. He gave Johny Ola a map of the Corleone compound, so Michael could be assasinated. Fredo didn't know that it was going to be a hit on Mike, but he was the one who gave Roth the perfect opportunity to kill Michael. But the attempt failed, as you know.

Well, it sounds like you have the definitive answer to one of our long-standing questions here.

Just wondering...where in the film does it say that?

Just thought I read that somewhere, I can be wrong. But Fredo did give information about the compound. Agree?

Those are some of the theories that have been bumped around on this very Board, when the question has come up of what exactly did Fredo do to help Roth.

But I've yet to see a definitive YES...he gave Ola a map or YES, he gave information about the compound itself.

Fredo would have to have been asked for assistance in a more subtle capacity. Some way that would not arouse his suspicion, just coddle him into thinking he's helping out but doing no drastic harm to Mike. Knowing Fredo, they would not have had to come up with too drastic a favor.

Apple

I think he opened the drapes.

In one of the posts there is reference to a GFII script on allscripts.com that contains a version of GFII. In this script it tells us that Fredo was contacted to help with the deal with Roth by Johnny Ola but he was guaranteed Michael was to be kidnapped only and not harmed. Assuming Fredo opened the curtains to have Michael whacked seems a little out of character. This sort of leads me back to my question from another post of whoever killed the assassins may have opened the curtains but I don't think it was Fredo.

Would love to see a link to that script! Hearsay never flys well after all this time.
allscripts.com =????

Some people here believe that Fredo opened the drapes to Michael's bedroom window so that the assassins could get a clear shot at Michael. It's safe to assume that the compound and Mike's house were reasonably well guarded during the party because of the hundreds (if not thousands) of people on the grounds, at least some of whom might be either enemies or thieves. But Fredo would have no trouble getting in and out of the house and the bedroom. If so, it'd put the lie to Fredo's later claim: "I swear to God, Mike, I didn't know it was gonna be a hit." What did he think the gunmen were going to do--watch Kay get undressed?

http://www.allmoviescripts.com/scripts/17584365683f3d9aa7445d6.html

fathersson, here's that link you'd love to see. I copied it from this post:
http://www.thegodfathertrilogy.net/ubb/ultimatebb.php?ubb=get_topic;f=1;t=004375

I will try to find the exact reference and copy it to this post later if you can't find it first.

Here it is I copied it from the script mentioned above.

MICHAEL
I want you to reach Fredo. I know
he's scared, but have one of our
people reach him. Assure him that
there will be no reprisals. Tell
him that I know Roth misled him.

HAGEN
My information is that Fredo
thought it was a kidnapping. Roth
assured him nothing would happen to
you.