Well that song is about Snoopy's most famous alter-ego, a WW1 flying ace in his Sopwith Camel (Actually the roof of his doghouse) on the hunt for the red Baron.
http://www.whatalovelywar.co.uk/war/images/snoopy.gif
I figure that some of you want to have a more logical explination behind that and so here it is.
This is a real Sopwith Camel
http://www.ctie.monash.edu.au/hargrave/images/sopwith_camel_original_500.jpg
Not really a dog house.
The Camel was successful in combat. It offered heavier armament and better performance than the preceding (Sopwith aircraft) Pup and Triplane. Its controls were light and sensitive. Agility in combat made the Camel one of the best remembered Allied aircraft of World War I. It was said to offer a choice among a "wooden cross, red cross and Victoria Cross." The Camel was credited with shooting down 1,294 enemy aircraft, more than any other Allied scout.
And THIS is the Real "Red Baron"
http://upload.wikimedia.org/wikipedia/commons/thumb/1/1a/Red_Baron.jpg/200px-Red_Baron.jpg
This is Manfred Von Richthofen "The Red Baron" the most succesfull fighter pilot of the first world war. He got the nickname "Red Baron" because of him flying blood red colored aircraft. Most famously a Fokker DR1 Triplane. If you were a pilot in the first world war and you had the misfortune to encounter Von Richthofen's blood red Fokker DR1 aircraft then you were pretty much done for.
http://1000aircraftphotos.com/AmateurBuilt/1777.jpg
As for how the Red Baron died, I'm sure we all know that it wasn't by Snoopy.
According to a Discovery channel program investigating his death, Manfred Von Richthofen was hit by an infanterist. A soldier who's name we shall never know who raised his rifle skywards and just by chance hit the Red Baron.
According to the photographic evidence and the seat of Von Richthoven's Fokker (which survived intact) the bullet went through his left buttock and into his intestines, the heavy internal bleeding was what killed him. According to eye witnesses, he landed his aircraft, crawled out, muttered "Kaputt" and died.
Von Richthofen was burried in France but with full honor, almost a state funeral, chivarly was still alive in those days.
Prior to his death Von Richthofen was working with Fokker on "the ultimate fighter plane" because although he was known for flying Fokker Triplanes, he wasn't really happy about the performance of that plane. The rotating engine made it difficult to keep level and the triple wings made it slower than it could be.
So Von Richthofen and Anthony Fokker himself went to work with his ideas and came up with what eventually became the best axis fighter of the war. The Fokker D7 which out performed every other allied fighter of the day. but by the time the D7 came about it was little too late. As a final proof on how right Von Richthofen was on how a fighter aircraft should be, the allied forces confiscated ALL D7 aircraft because of the potential thread they posed.
http://www.nasm.si.edu/research/aero/aircraft/images/fokker_dvii.jpg
A Fokker D7, the brainchild of the Red Baron and he never got a chance to fly it. This picture shows a replica.
"The stronger one gets the stronger one smells." - Son Goku, Dragonball Z.