You might believe it was the bands, the guitars, the hair, the costumes or the DJs. But the driving force behind the spread of rock and roll was none of these.

It was the outcome of a rumble between an 800-pound gorilla and the elephant in the room.

Throughout most of the 1930s and 1940s, General David Sarnoff, head of RCA and William Paley, the captain of CBS, battled over a replacement for the 78rpm record.

“Sarnoff and Paley both wanted to make record listening more convenient,” said Steve Propes,” author, record collector, and former rhythm and blues disc jockey, “but those guys hated each other.”

What started as a battle for the supremacy of convenience quickly turned into a bare-knuckle marketing brawl when the two men mixed it up in midtown Manhattan.

Paley, through CBS’s Columbia Records division, was working on the long-playing, or LP, record.

“The company had experimented with 7-inch records,” according to Propes, “but Columbia settled on a 10-inch LP at 33 1/3 rpm. A few years later they rolled out the 12-inch LP, which is how we know the LP now.”

An LP record held nearly four times as much music as a 78, and it didn’t snap, crackle, and break when you looked at it the wrong way. With CBS’s Microgroove technology, LPs sounded infinitely better than a 78. But so did a little old lady grinding the gears in her 1938 Chrysler. So perhaps sound quality wasn’t the LPs most interesting feature.

What caught people’s ears was the ability to listen to more than a half hour of music without changing records every four minutes. Round one went to Paley.

Sarnoff was not pleased. He, too, wanted to improve the convenience of recorded music.

From where he sat, high atop Rockefeller Center, one of the drawbacks of LPs was that the listener didn’t get to choose the order of the music.

And that’s where rock and roll and their brawl collided.

“They called it ‘Madame X’,” Propes said about RCA’s solution, which the company rolled out in March of 1949.

We know it as the 45rpm record.

“The 45 helped the teenagers claim rock and roll as their music,” said Propes.

Yes it did.

By the mid-50s teens realized how cool 45s were. The new discs were light, compact, durable, and affordable. Not only that, they were hip and quirky, just like their music.

Forty-fives were made for parties and sock hops. They were the perfect companion for reading Catcher in the Rye or solving math problems about men digging holes.

You put stacks of wax on the phallic-looking spindle and danced, or drowned out the world, for hours.

“Forty-fives also distinguished rock and roll from their parents’ music, which was on 78s,” Propes said.

The original discs were color-coded, with black representing pop music, yellow for children’s songs and stories, and cerise, a red-orange, for rhythm and blues—or race music as it was known in the white-bread 50s.

The color coding didn’t last long but while it did it was an outstanding marketing gimmick. Your records were black. Your little sister’s music was yellow. How cool was that?

Sarnoff didn’t stop there.

“RCA mailed packets of 45s to I don’t know how many radio stations.” Propes said. “They also enclosed a special record describing what 45s were all about. And then RCA offered to upgrade the equipment in radio stations, if the stations played 45s on the air.”

Those radio stations gave RCA a reliable market for its 45s while indelibly etching the 45 sound in the ears of teenagers.

And Sarnoff and Paley?

“Sarnoff offered CBS the opportunity to manufacture 45s if CBS would join him in establishing the speed as a standard,” said Propes. “Paley told him, in so many words, ‘Go screw yourself.’”

This was their last big brawl over audio. Both men were looking at a bigger picture—color TV. But, that’s a battle for another decade.

As for the 45’s distinctive look? Another marketing decision.

“I’ve never seen it spelled out,” Propes said, “but once you had a player with a big center you could only play 45s. Nothing I’ve learned has contradicted that.”

Forty-fives faded from the scene, leaving Paley to savor the ultimate victory. But if you think those A-side hits would have spread around the world as quickly as they did without Sarnoff’s humble 45 record maybe you don’t know the hole story.