The US secret service has a remarkable record when it comes to protection.

It was created in 1865 – not because of the assassination of Abraham Lincoln, but because of the rampant counterfeiting of money after the Civil War. The Secret Service is a subsidiary of the Treasury Department and was transferred to the newly created Department of Homeland Security in 2003.

It was not until 1901, after the death of a third president, William McKinley, that the Secret Service was given its actual task. It would be another five years before Congress decided to allocate money for presidential protection.

Theodore Roosevelt was the first to be protected. The initial force consisted of only two men.

Since then, 123 years have passed and there have been 20 presidents. Today, the Secret Service consists of around 3,600 agents and another 1,600 uniformed officers. Protection duties have been expanded to include presidential families, former presidents, vice presidents, candidates and foreign heads of state.

Despite all this time and growth, the successes are numerous and quiet. It is the incredibly rare failures that stand out. The assassination of John F. Kennedy in 1963. The shooting of Ronald Reagan at point blank range in 1981.

And most recently, a sniper attack occurred in Butler County. Former President and Republican candidate Donald Trump was injured. Volunteer firefighter Corey Comperatore of Buffalo Township was killed. The shooter, Thomas Crooks, 20, of Bethel Park, was also killed.

If you look at the numbers, the agency is successful. If you look at the costs, this is one of those jobs where there is no room for error.

At least five agents were given modified assignments following the investigation into the July 13 assassination attempt. One of them was part of Trump’s security detail. The others include the special agent in charge of the Pittsburgh field office and three other agents from that office.

These are not the first members of the Secret Service to face consequences. Several people were brought to Capitol Hill to testify. Kimberly Cheatle resigned as director less than two weeks after the incident. Further congressional investigations will follow.

And local police have been open about the failures that allowed Crooks to maintain his elevated position on a nearby rooftop – and those comments came immediately after the shooting.

“I told them that (expletive) on Tuesday,” Butler Township police Officer Drew Blasko said on the body camera footage. “I told them to put (expletive) people here.”

The Secret Service has been an effective and influential agency in its more than 100 years of existence. It has provided security for so many people – regardless of their party affiliation.

But one lesson from the Butler shooting is that sometimes a 99% success rate just isn’t enough.