With the start of the league year just days away, we're taking a deep dive into the stories behind some of the best free-agent signings in franchise history since the start of modern free agency in 1993. For the Broncos, free agency has been a key part of building Super Bowl teams, from the first in 1997 to the most recent in 2015.

Without question, the most significant free-agent signing in team history is Peyton Manning, and the legacy he left in Denver is still felt today.

How it happened

After the four-time MVP quarterback led the Colts to two Super Bowl appearances, a 141-67 record and eight division titles, a neck injury sidelined Manning for the entire 2011 season and the Colts decided to part ways with their future Hall of Fame quarterback. The move would uproot Manning's life and bring about perhaps the most-fervent free-agent chase in NFL history.

The frenzy began immediately, as Manning recalled in The Athletic’s oral history of the series of events. Even upon landing in Miami to spend time with his family, a helicopter awaited him.

Denver's head coach at the time, John Fox, was one of the first people to reach out to Manning, and the Broncos got the first meeting with the star quarterback on the mend. Their pitch centered on the talent at wide receiver with Demaryius Thomas and Eric Decker and at tackle with Ryan Clady. When it was done, John Elway asked Manning if he wanted to get a beer somewhere and employed subterfuge to stymie the local news outlets awaiting their next move outside UCHealth Training Center's gates.

"[A]bout 10 cars left the Broncos' facility, and it was like the president where you have these decoy cars," Manning told The Athletic. "You got (Broncos director of special services) Fred Fleming driving this way and Mike McCoy driving this way. And so me and John and (director of player personnel) Matt Russell were in one car, and somehow, we got away. … I do remember a couple of media telling me that they showed up at another bar, and Fred Fleming was right there at the bar having a beer, and he said, 'Y'all picked the wrong car.'"

The future Hall of Fame safety John Lynch — who signed with the Broncos when he entered free agency at a similar point of his career — joined the group, and after the get-together concluded, he felt good about Denver's chances.

"I left it thinking, 'Well, there's a good likelihood this is gonna happen,'" Lynch recalled to The Athletic.

Over the days that followed, Manning met with the Cardinals, the 49ers and the Titans, while about seven other teams had their bids declined, according to a 2012 report.

Meanwhile, his rehab from the neck surgery continued at Duke University, and the Broncos made the trip out to Durham, North Carolina to watch him work out.

"The one thing I knew about Peyton even before getting involved was that no one was going to outwork him," Fox said. "I knew it was not going to be the best he looked at that workout. He had to look decent, and he did."

As Manning turned over the decision in his mind, he was reminded of when he had to pick his college as a high schooler. Each choice had its positives, which made for a difficult decision. But Denver's roster — along with its coaching staff, front office and various other helpful factors — put it at the top of the group.

"Something about Denver just kept staying on my mind," Manning said. "I knew John Elway. I felt like he wanted to win now."

A little over a week after their first meeting with Manning, the Broncos had their quarterback. Dreams of Lombardi Trophies danced in their heads, but as Elway said at the introductory press conference, "This guarantees us nothing. It guarantees us a chance to work hard."

The outcome and impact

Manning's arrival in Denver immediately reshaped the Broncos' present and future.

The team, which was just months removed from its shocking overtime upset over the Steelers in the wild-card round of the playoffs, went from 50-1 odds to win the Super Bowl to 10-1 after Manning chose Denver.

And, in a way, his decision also affected the Broncos' past.

Ring of Famer Frank Tripucka happily allowed his No. 18 jersey to be unretired to allow Manning to continue wear the number that he famously wore in Indianapolis. That jersey would quickly become the league’s best-seller.

In the four seasons that followed, the Broncos enjoyed their most successful run since Elway's heyday. From 2012-15, Denver went 50-14 and won no fewer than 12 games in a season.

On the field, Manning was nothing short of remarkable. In his first season in Denver, Manning made quick progress in his return from injury and looked like his usual self with 4,659 passing yards and 37 touchdowns while completing 68.6 percent of his passes. Two seasons later, Manning was historically good, throwing for an NFL-record 5,477 yards and 55 touchdowns, earning the fifth MVP award of his career.

Manning also made a huge impact for Denver during the offseason. His presence was a major attraction for free agents like DeMarcus Ware, Emmanuel Sanders, Aqib Talib, T.J. Ward and Wes Welker, each of whom would be instrumental to the Broncos' success. His leadership also contributed to the development of receivers like Sanders and Thomas into star wideouts for years to come.

As a result, the Broncos returned to the heights they had last reached with Elway under center. They won AFC Championships over the Patriots in 2013 and 2015 and toppled the 15-1 Panthers to win Super Bowl 50.

With that win, Manning went out on top; a month later, he announced his retirement from the NFL. In the same place where four years earlier he had been introduced as a Bronco, he looked back on that moment with pride.

"When I visited Denver four years ago," Manning said at his retirement press conference, "if John Elway had sat me down and said, 'Peyton, here's what we're going to do. We're going to win over 50 games, win four straight division championships, lose only three division games in four years and none will be on the road, we'll beat the Patriots in two championship games and you're going to win NFL Comeback Player of the Year, another MVP, your offense will set single-season passing records, you'll break a couple more all-time records, and we'll go to a couple of Super Bowls.' I think I would have taken that deal."