I think this may have started with Bear Bryant; I’m not sure.
My question is: Has there ever been a coach,* IN THE US*, physically attacked, requiring a bodyguard?
Your title and question do not match. Law enforcement officers aren’t serving as personal bodyguards to coaches even though that is one of the obvious stations. Their job is crowd control in general and they are there to protect everyone including all the players, the fans and the general public. Crowds at large gatherings like sporting events and even concerts sometimes get out of hand so it is wise to have a law enforcement presence handy. As long as everything goes fairly smoothly, some of them just do crowd control at the end of the game so that everyone can get off the field smoothly and the coaches and players can move on to press conferences. Even high school sports often have a police presence for that reason and it has nothing to do with specific coaches.
There have been plenty of cases of large crowds getting out of hand even in the U.S. That is a dangerous situation that has to be protected against.
Personal police protection for the coach is a tradition that goes back at least 50 years. As the OP notes, is thought to have been started by Bear Bryant.
From here
As to the OP - sure football coaches have been attacked. Sean Diddy Combs was arrested for attacking his son’s football coach with a kettlebell weight.
Rap mogul Diddy arrested for ‘attacking his son’s football coach with a kettlebell at UCLA’
There seem to be a lot more attacks on high school football coaches than college or pro, so I guess the armed guards college and pro coaches get must be working.
Report: High School Football Coach Attacked In Office By Student
Parent Attacks Youth Football Coach for Ending Season Over Bad Attitudes: Officials
Suspect in Sharon High School football coach’s attack waives hearing
Middle Tenn. high school football coach hospitalized after student attack
Most high school level coaches have some sort of bodyguard even if you do not notice them.
In many areas high school sports is such a big business where you get many people pushing influence to get their kids playing time problems are going to happen.
They’re primarily there to protect the coach/help him move through crowds.
Actually, it’s only theoretically about safety. In reality, trooper presence is partly about ease of movement through fired-up (or liquored-up) crowds. And it’s mostly about status – for the coach and for the cops, who seem to excel at working their way into the background of TV shots.
That may be a regional thing; it’s not really seen in the northeast as far as I know.
Even if it hasn’t happened before, it’s not farfetched to think that a drunken fan attending a sporting event might go after the coach, so a few hours of a state troopers time seems a reasonable price to pay to deter this sort of thing.
Has happened … Tom Gamboa
He was attacked by hooded Afghan women?
I didn’t think they got so worked up over ball and strike calls. :eek:
And they were attacking a coach in 2002 to support a candidate in a 2009 election! Are you telling me they have … a time machine?! 
Seriously, the CBS News website screwed up, the photo has diddly-all to do with the story. Bare-chested father and son indeed. Sent an e-mail, although I doubt I’m the first person to notice the error in over 7 years.:dubious:
You are way off base. So much so that I wonder if you’ve ever seen the conclusion and immediate aftermath of a major college or pro game.
Hey, if you can’t be right at least be convincing. 
mmm
My point isn’t that coaches don’t have police officers close to them during the game - of course they do and they are the most visible ones especially for televised games but there is usually a lot more law enforcement presence at the game than that. My younger brother was an LSU police officer for years and part of his job was working their (very large and often rowdy) home football games among other events.
It isn’t just the coaches that are protected. The whole stadium is especially if there are VIP’s in attendance. There are usually officers in the admissions areas, some protecting parking areas and sometimes even plain-clothes officers in the crowd. The officers near the coach(es) aren’t there specifically to protect an individual coach even though that comes with it. Their location is just an obvious location to place officers to protect the field in general and provide crowd control, arrest trespassers etc.
I am fully aware that a few officers can’t control a crowd of thousands that gets out of hand but that doesn’t usually happen. Their job is to get the teams off the field and into a more secure area very soon after the game is over. It is mainly just basic crowd control tactics rather just a few people having personal bodyguards.
Yadda, yadda, crowd control and such. Okay if you’re playing at your home stadium and local police provide the control. What’s glaringly bullshit is dragging your own state troopers along on road trips to prop up your own sense of entitlement.
Need protection from drunken/belligerent fans? If I remember correctly, you’re traveling with 50+ players in the 6’ to 6’8" range weighing upwards of 280 lbs. who are real partial to you and work out on a regular basis. You have another group of 40+ in the 180 to 250 lbs. range who are also pretty quick and strong. Not to mention a bunch of overweight coaches and assistants.
It’s a status symbol for the coach, plain and simple. SCOTUS justices don’t have bodyguards; college football coaches sure as hell don’t need them (they are entitled to a US Marshals security detail when traveling outside DC, but apparently most of them decline it).
Aren’t college football coaches usually the highest paid employees in any given state?
Oklahoma’s Bob Stoops always has a monster follow him around every game. In addition to providing protection (which Stoops probably doesn’t need), he also performs crowd control.
Don’t run onto Owen Field. (Autoplay video)
The coaches get hit with Gatorade all the time. I know I’d want protection.
Then surely they could hire private bodyguards?
bingo !
Assuming you meant highest paid state employee, yes, they are. This link is a few years old, but in 27 states a football coach is the highest paid state employee, 13 states it’s a basketball coach, and in the remaining states it’s “dorks who aren’t even in charge of a team”.