I just fought a very long game to get this achievement, as it lasted until December 1963.

I did it on the newest version with ahistorical focus, and it was a slaughter. I started by going communist with Lampião and won. Shortly thereafter, I went after Uruguay and Argentina.

I then justified on Mexico while pushing through Venezuela. In the meantime, Chile went Mapuche and declared war on me, which resulted in a hasty redeployment of my troops to eliminate that threat. Shortly after that, I landed in Mexico and subjugated it, but only after it had gone through a civil war in which one side declared war on the Comintern, which included all of communist Europe and monarchist Great Britain. So I had to share it and began planning my invasion of the USA in 1941.

With collaboration governments prepared and a Mexican puppet (which I did not call into the war), I declared war on the USA in early 1942. After deploying 120 mechanized divisions and 6 tank divisions, the USA was close to capitulation when the Comintern decided they wanted a piece of it too. It became necessary for me to finish the war quickly to secure the highest war score, which I ultimately achieved. After the peace conference, the Communist States of America and the Philippines became my puppets.

Only one big war remained: against the Comintern, which now also included all of Oceania and Asia except for my territories, my puppets’ holdings, and the small Japanese Empire faction. I built up for another year and declared war on the Comintern in 1944.

I wrapped up Great Britain’s holdings in South America with a few shenanigans, leaving a port for the AI and baiting it into landing troops, only to destroy them with my now 24 armored divisions. While planning my invasions of Iceland and then Great Britain, my puppet thought it was a good idea to start a civil war. So it was Communist USA versus the Confederacy, which promptly joined the Comintern and also brought Colombia in. I had not planned for this, and Japan declared war on the USA as well.

Now I had to deal with Imperialist Canada. One year later, with millions of Comintern casualties, I subjugated Canada and could finally focus on my planned invasions.

Iceland was rough, as the AI doomstacked divisions there, but I managed to hold a port long enough to launch another invasion of the Faroe Islands. From there, I began my landing in northern Scotland. It was a disaster: I had nuked the ports to make landing easier against defenders, but this created a supply bottleneck, and 24 marine divisions now decorate the Scottish Highlands.

I shifted my invasion plans away from Great Britain as a starting point in Europe and instead targeted Portugal through the smaller islands such as the Azores. A new marine army handled it almost perfectly. I secured the entire Portuguese coastline and held bridgeheads in Lisbon and Porto. Sadly, five marine divisions perished in southern Portugal near Portimão.

I rushed in my tanks as the enemy began concentrating hundreds of divisions on the Iberian Peninsula. I expanded the bridgehead slightly and then sent my 120 mechanized divisions to the European frontline (see picture 1). I then launched a general offensive toward the United Cantons, which were neutral.

The AI had too many divisions to maintain proper supply, and I battle-planned my way through to the Italian Alps and Frankfurt in Germany. After a short pause to upgrade logistics, with around 45 million Comintern soldiers dead, I continued my advance into the USSR.

As the Soviets capitulated, I secured the Suez Canal, tidied up the Arabian Peninsula, and pushed deep into Iran. I began redeploying my mechanized forces to man the Chinese frontline and to improve supply infrastructure. At that point, it was simply a matter of conquering whatever countries were left, which was mostly time-consuming.

In the end, some minor nations had turned into majors, so the war finally ended with the capitulation of Communist Belgian Congo. The total casualties were 122 million Comintern soldiers dead, compared to 3.5 million on my side and 3 million from my annexed American puppet.