Just about the most unrealistic what-if of WW2.
Germany collapsed like water against a unbreakable Luxembourgian Schuster Line and consequent relentless Luxembourgian counter-attack, as dozens of thousands of German troops were surrounded and destroyed, with Luxembourgs population soon to be outnumbered several times by German POWs.
Reinforced by French troops, Luxembourgian's 400 Neo-Spartans making a daring push towards Wilhelmshaven, crushing all resistance and entrapping the vast majority of German's army in the Low lands.
German OKW orders a breakout to the East, but though scattered, sections of around 10 Luxembourgian troops succeed singlehandedly in wiping out entire German divisions at key checkpoints who the German OKW never expected such a stiff resistance could be made.
With the German invasion army utterly wiped out, Allied politicians and generals pushed for an invasion under their oversight. Minister of Defence Perre Dupong warned that only a Luxembourger-led invasion would have the approval of Luxembourg. Laughed away by Paul Reynard and Winston Churchill, along with their respective High Commands, the Allied armies proceeded to engage in a general offensive, with British troops landing in the Netherlands and the Atlantic coast of Germany, while French troops advanced North through the low lands with the intention of circumventing the Southern part of the Siegfried line.
It was a bad decision. Luxembourger troops allowed the British armies to establish a beachhead, but soon enough a force of 50 attacked the resupplying British, only a paltry force escaped to the Netherlands, with the Luxembourgers the entire BEF prisoner. Churchill called it "the worst British defeat in history". The British were out of the war, at least for the time being. Likewise, the French occupying forces in Germany were quickly surrounded and destroyed by around 200 troops, while the French troops moving through Luxembourg were likewise crushed and pushed back South. After a couple of engagements between Belgian troops who advanced to Luxembourg were beaten back, both countries dared not support any Allied attack on Luxembourg.
Leaving roughly 200 holding Luxembourg and the Rhineland all the way to Bremen, the other half of the Luxembourger army engaged in a general offensive towards Berlin, with the German forces that didn't melt away and desert were quickly destroyed. Soon Germany was in shambles, with strikes and general dissent happening everywhere. After occupying Magdesburg, Luxembourger troops divided their army in half, with the new destination being Vienna. The large territory being covered needed a garrison, so Luxembourger authorities put their large population of German PoWs to work as occupying forces. Immediately the Luxembourgers were cheered and hailed as liberators from Nazi oppression. Upon entering Berlin, the occupying army revolted and arrested Hitler, and pleaded to work for Luxembourg. By then, Luxembourger Southern forces had reached Munich, with no resistance. Negotiation with the new German authorities came to an end. The provisional Fuhrer of Germany, Alfred Jodl, agreed to an armistice and immediate integration of Germany into Luxembourg. The Luxembourger troops that arrived in Vienna were greeted as heroes. Luxembourg authorities set about to restore the independence and sovereignty of the Post-Munich Czech State, along with a Polish State with the pre-WW2 borders, as far as the German side was concerned. Luxembourg authorities declared that the Soviet invasion of Eastern Poland was a matter that wasn't of Luxembourgish concern, and should be brought up and solved by the soon independent Polish authorities, alongside other concerned States, to the Soviet Union.
Now with a large army to boot, Luxembourg left 50 Luxembourger troops spread out across the new Luxembourger States, and brought the rest back. The Luxembouger army then demanded the immediate surrender of the Belgian and Dutch governments, as they were integral parts of the old Luxembourger possessions, with the addition that their very culture were a part of the Luxembourger family. Both governments, pressured by the Western Allies refused. But a combination of large scale riots and popular uprisings alongside the advance of the Luxembourger army there made both governments relent. Dutch and Belgian armies then began fighting the French allies, as both monarchs petitioned for their territories to be annexed to Luxembourg, and for their demotions to nobility of lower rank. For their quick surrender, Charlotte of Luxembourg demoted Wilhelmina of the Netherlands and Leopold of Belgium just to Counts of Schiermonnikoog and Oudenaarde respectively.
Luxembourger troops advanced on the French troops still on the Lowlands and quickly destroyed most of them, and proceeded to turn South. French efforts faltered and collapsed as the Luxembourger armies won victory after victory. Paul Reynard resigned and was replaced by Marshal Petain, a very Luxembourgphil, who under the pressure of the population as usual, aceded and requested an armistice and annexation to Luxembourg, which was duly conceded. With Luxembourg now dominating Europe, and the reason for the war now partially amended, Churchill was highly pressured in Parliament to sign an armistice with Luxembourg. He steadfastly refused and was defeated in a motion of no confidence, and replaced with Lord Halifax, who with the British King's blessings signed an armistice with the Luxembourger duchy. Soon enough Luxembougers and British were cooperating to overcome the Soviets, who steadfastly refused to let go of their militaristic conquests.
Is this less realistic than a Japanese invasion of the US?
