The Chicago Bears are historically famous for their great defense, as their only Super Bowl victory came behind one of the greatest defenses of all-time in 1985. While the Bears are far from the greatness of that team, their front office is clearly focused on building their defense and has made some significant acquisitions through free agency. 

The Bears landed one of the top free agent linebackers on the market when they signed Super Bowl Champion linebacker Danny Trevathan to a four-year deal, and they are not done bolstering their defense, as they have agreed to terms with another notable free agent linebacker Saturday.

Former Colts linebacker Jerrell Freeman has agreed to a three-year deal with the Bears, which is reportedly worth $12 million and includes $6 million guaranteed and $2 million in incentives. The Bears' new linebacker recorded 112 combined tackles, three sacks and an interception last season with the Colts, and he is heading into his fourth season in the league.

Freeman finished the 2015 season as one of the league's best run-defenders at the linebacker position and is expected to make an immediate impact on Chicago's defense. The former Colts linebacker became a starter his first season in Indianapolis after transitioning from the CFL and has proven to be an athletic linebacker that can stop the run and also drop back in coverage. The Bears' newly acquired linebacker joins Trevathan, who led the Broncos in tackles last season with 109 combined tackles, and the two could make a strong combination in the middle of Chicago's defense in 2016.  

The Bears are clearly focused on their defense and have reportedly retained defensive lineman Mitch Unrein on a two-year contract. The Bears defensive lineman was picked up last season after being waived by the San Diego Chargers, and he recorded 18 combined tackles and a sack in 14 games.

The team improved defensively under first-year head coach John Fox last season, going from 31st in the NFL in terms of points allowed in 2014 to 20th in the league last season, and it is only looking to continue to improve in 2016. It will be interesting to watch how this Bears defensive comes together next season, but there is no doubt that they have made an upgrade at the linebacker position and could look to be contenders in a tightly fought NFC North division next season.