It is worth pointing out that the US and British were actually successful in defeating insurgencies in the immediate postwar era, as witness the results of the Greek Civil War and the Hukbalahap Insurrection in the Philippines, as well as various anti-guerilla campaigns during the Korea War.
If you are a major power willing to accept a few thousand casualties like the U.S. in the Philippines then defeating insurgencies usually isn't that hard. Compared to the normal conventional battles of the time a insurgency would be considered a nuisance to the armies of the era.
More recent restrictions on the force that can be used by Western powers against insurgents and much greater risk aversion for casualties makes insurgencies harder to deal with in the modern era.
Still we often forget that the South Vietnam wasn't beaten by an insurgency. It was beaten by a conventional army and even in Iraq when we left there was no insurgency and hadn't been one for a number of years.
Insurgencies batting averages are historically quite bad.
Off topic to the thread but I must say that even with all the news that you'd think would otherwise replace its spot on the front page the fact that Rommel's death having been found out to be forced suicide making it gives me a nice chuckle. The Wallies really did have a hard on for him didn't they?
There are reasons for that, reasons that don't make nearly so much sense from a modern prospective, but lets just say he was the face of the Germany Army for the Anglo-American world from 1941 thru 1944.
You went into a movie theater in 1942 in most small towns and all cities in America or Britain you had a film reel of war events. It was the first war where some of the generals started holding interviews and press conferences during the war to give war updates (not so much in the Eastern front) that much of the world got to see parts of during the weekly film reels before movies and cartoons all around the developed world.
https://www.youtube.com/watch?v=vMsrjOZsxbI
https://www.youtube.com/watch?v=SfSr_13hJtM
It turned the military commanders into universally known public figures.