Dennis Prager chose Andrew Roberts to teach the latest Prager University course, in part, for the British historian’s moral clarity.

“Some people and regimes and ideologies have inflicted unspeakable suffering on people and he knows that,” Prager says of the online course dedicated to the U.S. Armed Forces.

The longtime radio show host also wanted to avoid choosing an American intellectual who could be accused of being a “homer” when it comes to U.S. military measures across the globe.

In “Why America’s Military Must Be Strong,” Roberts details the good that American might has achieved throughout our history, a notion foreign to many on the left, Prager says.

“The United States military has repeatedly made the difference between civilization and barbarism,” Roberts says during the five-minute course. “A militarily strong America is the one indispensable prerequisite for a peaceful and prosperous world.”

The course recalls the threats to global peace past and present, from the rise of Nazi Germany to our current battle against radical Islam. It also reminds students the difference between a militarily strong U.S. and a relatively weak one.

When America had the 14th largest army, Adolf Hitler saw it as a sign that part of the west wouldn’t be vital enough to dissuade his plans, Roberts argues. Decades later, a robust American military under President Ronald Reagan’s watch stared down a new threat.

“Even a superpower like the Soviet Union has to acknowledge its own internal contradictions and inability to ignore the west,” Roberts says.

The left’s consistent criticism of the U.S. military and its admittedly large budget works as a force against such strength, Prager says. He also notes how previous generations would have viewed the current battle against global terrorism as opposed to what we often witness today.

“There would have been a clarity about who the enemy is … not all of Islam, but in fact those religious Muslims who wish to see Sharia dominate society,” he says. “If you can’t name your enemy it’s harder to fight them.”

Like other Prager University courses, Roberts’ lecture doesn’t last much longer than a music video, length-wise.

“We do believe we you can change minds in five minutes … and really confront people,” Prager says.

The talk show hosts adds the course should act as a refresher course for those who fail to put the country’s military muscle in context.

Americans need to be reminded that for so many people the vision of American soldiers heading their way is a “blessed sight,” he says.