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One fall night 25 years ago, Art Shell climbed into bed. He was watching Nightline when the phone rang. It was Al Davis, owner of the Oakland Raiders. It was a call that would begin to change everything.

"I'm thinking about making a switch," Davis told Shell. "I'm thinking about making you head coach of the Raiders."

Shell initially sat up in bed. His heart began beating rapidly. Mike Shanahan was currently the head coach, and Shell the offensive line coach under him. Davis had caught Shell totally by surprise. So much went through Shell's mind, including the fact he would be the first black head coach in the modern era of the sport. Shell climbed out of bed.

"You understand the Raider way," Davis said. "You're a leader. You're smart. You work hard. Everyone respects you, so you're the perfect choice. Think about it and get some sleep."

Then Davis hung up.

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Shell had dreamed of being a head coach. As maybe the best offensive tackle in history, he prepared like a coach, anyway. During his playing days, he was studious and a workaholic despite having immense physical skills, leading Davis to call him "coach" in passing and John Madden to tell him he would make a great coach if that's what he wanted to be.

"How do I become a head coach in this league?" Shell had once asked Raiders coach Tom Flores.

On the surface, it was a crazy question. Not only were there no black head coaches, but there were almost no black assistant coaches. In 1980, nine years before Shell, there were only 14 black assistants out of 262. That number only slightly increased a short time later.

But Flores didn't blink. He told Shell to study and work hard. Shell already knew how to do both of those things. From that point on, Flores was among the supporters of the idea of Shell becoming a head coach.

There he was, on the verge. A great, all-time Raider who would become not just coach of the team he loved, but also the first black coach since Fritz Pollard headed the Akron Pros in the 1920s.

That phone call from Davis would begin Shell's historic, brilliant odyssey, which in turn would open the door for many more African-American head coaches to come. A legion of men owe so much to Shell, from Denny Green to Tony Dungy to Marvin Lewis to Herm Edwards to Mike Tomlin. In many ways, their careers trace back to Shell and when he coached his first game as an NFL head coach 25 years ago.

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The game today isn't as diverse as it should be, but it has grown considerably, and in many ways that growth can be traced directly to Shell.

While the growth of African-American coaches was excruciatingly slow, it has reached a point now, where the color of a coach's skin, while not irrelevant, is getting close to that point. That's the lesson Shell's story teaches us today.

Because of persistence from Shell and others, and the efforts of the NFL, including former commissioner Paul Tagliabue, the number of black assistant coaches coaches went from a paltry 14 in 1980 to 199 out of 610 in 2012, or 32.6 percent. Twenty-five years ago, Shell was the only black head coach; now, after years of denial of opportunities, the number of black head coaches is four (Lovie Smith, Mike Tomlin, Jim Caldwell, Marvin Lewis).

That isn't exponential progress, but it's progress. Slow, deliberate progress. Much of the credit, again, goes to Shell.

Shell learned how to coach by listening and preparing. "I'd listen to Gene [Upshaw] answer the questions," Shell said in an interview with The New York Times' Thomas George in 1989. "He always said the right things and he was so good, so quotable.

"I paid close attention. I learned a lot that way about football, about life, by just listening."

He told Sports Illustrated's Jill Lieber in 1989 what he learned from the various coaches he worked under. "John Madden taught me about the game of people," Shell said. "I learned that you have to understand each individual, when to push his buttons and when not to. From Tom Flores, I learned patience. He was a quiet, stoic leader. Mike Shanahan was one of the most organized people I ever met."

Shell was ready.

Yes, so much went through Shell's mind after that phone call, but what didn't was going back to bed.

"I don't know how in the hell Al thought I was going back to sleep after that call," Shell said.

Shell went to the Raiders facility the morning after the call, and Davis made it official. "You understand the Raiders," Davis said.

Shell's next stop was a press conference. It was packed. The story had become national, but Shell remained calm and measured. He didn't, however, downplay the importance of the moment.

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"It is an historic event; I understand the significance of it," Shell said at the time. "I'm proud of it, but I'm also a Raider. I don't believe the color of my skin entered into this decision. I was chosen because Al Davis felt I was the right person at the right time. The significance in this is I am now the head coach of the Los Angeles Raiders. We're going to try and regain the power, toughness and explosiveness we had in the past."

"If this is an historic occasion," Davis said at the press conference, "it will really only be meaningful and historic if he is a great success."

Davis told The New York Times' Dave Anderson in 1989, "I wanted a Raider. When we went back to Oakland for an exhibition game two months ago, the one thing lacking was a link to the past in our coaching leadership."

Then Shell had to do something uncomfortable. Shanahan's relationship with Davis had become toxic. In the end, Shanahan and Davis came to truly despise one another. Shell called a staff meeting, and in that meeting were assistants loyal to Shanahan.

"There may be some of you that don't want to be here," Shell told the room. "My office will be open all the time. If you want to talk, we can talk."

Shell wasn't certain if any staff members would quit out of loyalty to Shanahan. None did. It was a testament to the respect Shell had earned in his decades as a player and assistant coach.

Monday night came, and hours before the game Shell sat in his hotel room. He thought about everything, but mostly his thoughts focused on the football game. Then he smiled.

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"Al wanted this history to be made on Monday Night Football," Shell says now, as part of an extensive interview with Bleacher Report. "He wanted the extravaganza. He wanted that big stage."

The Raiders were in last place in the AFC West, and their opponent, the Jets, were in last place in their division. The game was scoreless in the first half, and Shell knew what was wrong. The players were pressing and were tight because they wanted to win the game for him. His halftime speech to the players addressed the problem directly.

"I want to win this game, too," Shell told the team, "but not for me. I want to win for the Raiders. So relax and play smart."

They did. A 73-yard touchdown pass put the Raiders on the board, and with the score tied in the fourth quarter, the Raiders intercepted Ken O'Brien for an 87-yard pick-six. Shell had implored the Raiders to play the game for themselves, but what they ended up doing was winning it for him after all. They beat the Jets 14-7, and that game went down in history.

The locker room afterward was ecstatic. Every player hugged Shell. Shell remembers one of the biggest congratulations he received was from Raiders defensive lineman Howie Long, who would later join Shell in the Hall of Fame.

It was a desperately needed win, but everyone knew it was more than that.

Every game afterward that year, no matter the city and no matter the opponent, players—particularly African-American ones—would approach Shell before and after the contest congratulating him on being the head coach. The Raiders games themselves that year were primary, of course, but acknowledging Shell and the moment, all that season, was almost as important.

The Raiders that year went 7-5 under Shell, finishing 8-8 overall and missing the playoffs by a single game. The next year, they went 12-4 and reached the AFC title game.

Shell wasn't the only one making history. One year earlier, at the beginning of the 1988 season, Johnny Grier had become the NFL's first black referee. Shell remembers several weeks after beating the Jets, he and Grier were speaking before one game. Shell had recently received some hate mail, and he relayed to Grier, who had officiated that Jets game, the contents of one letter in particular.

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"You and your n----r referee," the letter read, "cheated the Jets out of a win."

Shell told Grier, "You know you're my n----r referee, don't you?"

Grier and Shell both chuckled. It was their way of mocking the hatred.

To understand how Shell became a part of history, you have to understand the man who made the decision. For all of his quirks and faults, Davis was a pioneer, far ahead of his time. The things Davis did to diversify the Raiders remain unmatched in football and may never be equaled.

When Davis coached the Raiders, he made a statement against segregation when his team was scheduled to play a game in Mobile, Alabama. Davis pulled his team to protest Alabama's segregation laws. He got the American Football League's All-Star Game moved from New Orleans to Houston because of that city's segregation laws.

Davis was also one of the first to sign players from historically black colleges into the pros. One of those men was Shell, whom Davis signed out of the University of Maryland Eastern Shore (then called Maryland State College).

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Decades later, as head of the Raiders, the hiring of Shell and others on the team was simply a continuation of Davis' beliefs in balancing winning with equal opportunity. He'd go on to hire Tom Flores, the first Latino coach to win a Super Bowl, and Amy Trask, the first female chief executive to run the Raiders' business operations.

Shell was an excellent coach, Flores won two Super Bowls, and Trask is a Hall of Fame candidate.

"Al hired Art for all the right reasons—he hired Art as he always hired: without regard to race, ethnicity, religion or gender," Trask wrote in an email to Bleacher Report. "Al did this well before anyone else—and to a greater extent than any others do to date."

I've known Shell for decades, and there are few men, in any walk of life, who were smarter and more decent. But it was one of Shell's most defining qualities that made him perfect to be a pioneer: his calmness.

Some criticized Shell for it, saying he was too distant, but they didn't understand. As a player, Shell always believed that you played smarter when under control. As a coach, he felt the same. It was more than that, though. Shell knew that everyone was watching. He wasn't just coaching for himself or the Raiders; he was coaching for black men that would follow.

A white coach could be boisterous or scream or leave tickets for Elvis the way Jerry Glanville did. Or get cocky with the press like Bill Parcells. The double standards of race meant Shell had to constantly be uber-professional, which wasn't a problem for him, because that's who he was.

Shell had two coaching stints with the Raiders. His second lasted a season—but it's that first one, the historic one, where Shell made his mark. Shell coached the team in that first stint for six years, going 54-38. To this day, that stretch is one of the most successful in Raiders history. Davis fired Shell after the 1994 season, something Davis would later say he regretted.

After the Raiders came NFL assistant coaching jobs, but then Shell went to New York to work for the league office, first in the office of college relations and then in the appeals office, handling player discipline. He served as the NFL's senior vice president of football operations and development beginning in 2004.

And now?

"I'm totally retired," Shell said.

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He's 67 now, and this past week he went to see his nephew play high school football. "You work all of your life," said Shell, "so you can enjoy family and friends. Travel to see people and enjoy life as best you can."

Shell's legacy? Twenty-five years ago, a forward-thinking owner gave him a unique opportunity, and Shell proved Davis right, while simultaneously making history.

"Fairly early in my career, and after Art was named head coach, we were at a league owners meeting," Trask remembered. "One night while there, the Raiders contingent went to dinner, and as I listened to Art share stories, reflections and anecdotes from his career, I understood that not only was Art a giant of a man on the field, but off the field as well. Art exemplifies the best of not only the Raiders, but the National Football League."

Mike Freeman covers the NFL for Bleacher Report.