On Thursday night, a sniper gunned down four of his Dallas police officers and killed another officer.
Shortly after he earned the rank of chief, Brown lost his own son in a police-related shooting -- after his son shot and killed an officer.
As Brown prepares for several police funerals, he faces yet another grueling challenge: trying to lead a grieving department amid anti-police tensions across the country.
"We're hurting. Our profession is hurting. Dallas officers are hurting. We are heartbroken," Brown said. "There are no words to describe the atrocity that occurred to our city. All I know is this: This must stop, this divisiveness between our police and our citizens."
The sniper who killed five officers Thursday night was bent on killing white officers, Brown said.
What the gunman might not have known was that four of the Dallas officers he killed worked under the command of a black police chief -- one who rose from the challenges of a tough south Dallas neighborhood to become the top cop of the country's ninth largest city.
Growing up in a rough area, Brown understood what it's like for many to have a negative impression of police.
"You stay away from the police in my old neighborhood," Brown recalled to the Dallas Observer
earlier this year. "You get the police; you get in trouble."
But after he came back from college in the early 1980s, he saw the crack cocaine epidemic slowly destroying his neighborhood. He couldn't watch his hometown deteriorate.
"I began thinking about law enforcement then," he told the Observer. "I wanted to do something rather than just complain about what was happening."
So in 1983, he earned his Dallas police badge. Five years later, he suffered his first major tragedy on the force: the on-duty death of his former partner Officer Walter Williams
"When things like that happen and you're really close, you don't believe it for the longest time," Brown told The Dallas Morning News
in 2010. "I really relate to all of those in-the-line-of-duty deaths (on a) much more personal level."
Then, in 1991, Brown's younger brother, Kelvin, was killed by drug dealers
in the Phoenix area. The chief rarely talks publicly about his brother's death.
But Brown overcame the tragedies and climbed up the ranks of the Dallas Police Department. In 2010, he became the police chief, leading a force of 3,600 officers.
That's when the job got extraordinarily difficult.
A mountain of tragedies
Just weeks after Brown was sworn in as chief, a gunman killed an officer from the nearby Lancaster Police Department and a young father on Father's Day 2010.
The cop killer turned out to be the police chief's son, David Brown Jr.
Lancaster police responded to the scene and fatally shot Brown Jr. more than a dozen times. An autopsy revealed he had PCP, marijuana and alcohol in his system, CNN affiliate KTVT
The newly minted Dallas police chief was at a loss for words.
"My family has not only lost a son, but a fellow police officer and a private citizen lost their lives at the hands of our son," Brown told his department, according to The Dallas Morning News
. "That hurts so deeply I cannot adequately express the sadness I feel inside my heart."
New style of policing
Despite speculation about whether he would resign, Brown moved forward, charting a new course for the Dallas Police Department.
Mayor Mike Rawlings credited the police department with training in conflict de-escalation techniques "far before cities across America did it."
"We are one of the premiere community policing cities in the country. And this year, we have the fewest police-officer-related shootings than any large city in America," the mayor said. "So we are working hard to improve, and there's always room for improvement. But we are best in class."
Another method emphasized by Brown: community policing, which promotes proactive interaction between officers and residents.
While some critics slammed community policing as a waste of time, Brown insisted that it led to lower crime rates as well as lower tensions between residents and police.
"In my opinion, how can you argue with aggressive community policing if it has yielded the safest the city has been over 86 years?" Brown told the Observer
That emphasis on police connecting with residents was evident just hours before the killings Thursday night. Even while many demonstrators were demanding police accountability, some officers took time to chat with protesters, even taking selfies with them.
"We saw police officers shaking hands and giving high fives and hugging people and being really in the moment with us," demonstrator Sharay Santora said.
Minutes later, the sniper opened fire on police protecting the crowd. Four Dallas police officers and a Dallas Area Rapid Transit officer were killed. Is was the deadliest assault on U.S. law enforcement since 9/11.
Thanks for a thankless job
One day after the deaths, Brown addressed a massive crowd of supporters gathered in the city's aptly named Thanksgiving Square.
"In the police profession, we're very comfortable with not hearing 'thank you' from citizens ... who need us the most," the chief said.
"So today feels like a different day than the days before this tragedy, because you're here. Because Dallas is a city that loves."