As I read the Noevl and watch the movie I have come to the Conclusion on something.

In the Novel, During the Mob war after Sollozzo's murder and McClusky's killing I think the Corleones were attacked only by both the Tattaglia's and Barzini Families. It said Cuneo lived far upstate New York with his operations. Stracci lives further in the state of New Jersey along with his operations. I figured they wouldn't want to get mixed up in the war in the 5 Boroughs of NYC since they are such a distance as the Novel put it, even though Stracci was confirmed to be against the Corleones decision on Drugs. I don't think they would risk their Families in the war like I said before. Why else do ya think Mike didn't have them killed along with Barzini and Tattaglia as well as Fabrizio?

In the Movie I think all of NY Families teamed up against the Corloenes since they live so close together in the 5 Borroughs in NYC. The Movie made it different from the Novel. Cuneo lived in the Bx, Stracci from Staten island, Tattalgia from BK, Barzini is a good question. And that's why Mike had all 4 men killed together during the baptism. Because all 4 Families supported Sollozzo.

Just thought I should say this. Let me know your take on this

I think you're right, BofB. The novel calls it "The Five Families War of 1946." But since Stracci and Cuneo weren't killed, the most likely reason that Michael didn't move against them is that they didn't side with Barzini and Tattaglia during the war--or at least didn't take an active role in the fighting. And, yes, the novel does say that they weren't physically located in the Five Boroughs of New York, so territory might have been a factor. The film, of course, had all of them inside the borders of NYC.
Geography wasn't a factor in real life. In the famous Castellemmarese War of 1930-31, Capone (Chicago) helped Masseria (Brooklyn), while Magaddino (Buffalo) helped Maranzano (Brooklyn). Other out-of-towners also pitched in.

I had no idea Capone had any kind of friendship with Masseria. But the Buffalo Boss was Bonnano's cousin, right? I guess in that real life situation they were calling eachother for help to win the war. And I guess out-of-towners were also called by both sides for help.

Masseria went to Chicago to enlist Capone's help. In return, he promised Capone (a Neapolitan) help with the Sicilians who were running the local Mafia, then called the Unione Siciliano, under the leadership of Joe Aiello, a Capone foe. You're right: Magaddino was Bonanno's cousin. He saved young Joe's life by defending him in a sit-down over a territory dispute long before Joe became Don. His help to Maranzano was offered because Magaddino, like Maranzano, was a Castellemmarese. Later Magaddino and Bonanno became enemies. Magaddino pressured the Commission to remove Bonanno as the head of his own family. Bonanno says Magaddino kidnapped him in 1965. Others say Bonanno did his own disappearing act to escape Federal warrants and Commission assassins.

This is what I believe happened during the Mob war in the Novel.

A bomb had exploded in the mall which was thrown from a car that sped off. I believe the Tattaglias did this trying to avenge for what happened to their son, Bruno.

In the downtown area, 2 Corleone Button Men were killed when they were in Greenrich village. My guess is that this was an attack from the Barzinis.

Later on, in the Novel, The Barzini and Tattaglia Families were smashing through the Corleone Family territories: Bookmaking, Garment Center, Union locals, and policy bankers. They even killed a few officials who ran some of those businesses as well as kicking them away. (This was when Sonny was still the acting boss while the Don was still slowly recovering)

When the Corleones first retaliate it says that they killed someone so important that they wish to hide his body. My question would be who do ya think is so important??

When the Corleones retaliate again they massacred Dock goons (Which is owned by the Tattaglias). They killed Tattaglia Family Pimps. And when the Bookmakers were still kicked oiff their property Clemenza's regime was sent to wreak havoc on the shore. My guess is that these were Barzini's people who were invading the businesses over there since it was one of his ambitions to take over part of the Corleone gambling operations

I don't recall that from the book.

I think you may be mixing up the scene when, after Hagen calls Bonasera to redeem the favor which Bonaserea owes Don Corleone, Bonasera speculates to himself, not yet knowing the service which Don Corleone sought, that perhaps the Corleone family "had killed somebody so important that they wished to hide his body, make it disapppear, and what better way than to have it officially buried by a registered undertaker?"

Sonny, of course, tries to coordinate a massacre of the heads of all the other families, and there's various mentions of the Corleones fighting multiple families.

There is a very curious line in the Peace Conference scene, though: "What was more inportant was that Barzini by speaking out was saying that if peace was not made he would openly join the Tattaglias in their war against Corleones." Are we to think that, to that time, Barzini had appeared to be a bystander as Stracci and Cuneo were?

The novel says Barzini "had supported Tattaglia with money and influence since the start of the war."