DENVER—As the Ravens prepare to face the Broncos in Sunday’s AFC divisional playoff game, reports from both cities confirmed Friday that the matchup has rekindled much of the underlying animosity still simmering from the infamous Baltimore-Denver War Of 1877.

The conflict, the most violent in U.S. history according to military scholars, left over 12 million dead. Sources said feelings of resentment and anger between the residents of Baltimore and Denver are still noticeably palpable today.

“Despite the fact that over a century has since passed, a great deal of bad blood remains between these rival groups,” said Regis University historian Dr. Kyle Larson, explaining that the full-scale war erupted after Denver officials sent an army of 40,000 soldiers into Baltimore to quell violent protests of Colorado’s admittance to the Union. “The horrors of those barbaric times are forever woven into the history of these states.”

“There are still many residents in both cities who lost relatives in that war,” Larson added. “Though some families were sadly wiped out entirely.”

Larson told reporters that of the roughly 17,000 battles during the 12-year war, the most notable was the Fort McHenry Massacre, in which Denver soldiers ruthlessly shot and killed 63 Baltimore militants after they had already surrendered their pistols and muskets. According to historical accounts, a militia of Baltimore residents armed with sabers and torches then retaliated by riding cross-country on horseback and burning down the entire town of Cherry Creek in Denver, slitting the throats of every man, woman, and child in their path.

Though the two warring factions reached a ceasefire in 1889, violence has frequently flared up between both sides over the subsequent years, and many around the country are reportedly fearful that Sunday’s game will reignite tensions once again.

“Although this is a highly compelling matchup between two potential Super Bowl contenders, we cannot forget that, for many in Baltimore and Denver, this is much more than a football game,” said Sunday NFL Countdown host Chris Berman, adding that extra security and armed police officers will be on hand to defuse any potential violent confrontations between the two sets of fans in and around Sports Authority Field at Mile High. “Obviously one of the biggest storylines revolves around wide receiver Eric Decker, whose great-grandfather served in the 83rd infantry division of the Baltimore army and died in a Denver POW camp. Many in Maryland see him as a traitor for wearing the Broncos' colors today.”

“But while emotions may run high, we’re all keen to avoid an incident similar to that which occurred the last time these teams met in the playoffs in 2000, when 132 people were tragically beaten to death in a brawl that broke out in the stands in Baltimore,” Berman added.

Reached for comment, a league spokesman confirmed that a moment of silence will be observed before kickoff to commemorate the lives lost in a 1962 flare-up of the conflict, when Denver warplanes dropped a five-megaton nuclear bomb on Baltimore that instantly incinerated over 400,000 people.