This scenario can be very easy, if you play it right.
The best way to win this level is to conquer and hold Brazil as soon as you can, and to make sure it does not fall into the hands of a stronger player.
Start by placing all your reinforcements in the Eastern United States – attack Central America and surge to Venezuela.
At this point, you want either red or purple to have Brazil – it doesn’t matter which because both are in very weak positions.
On your second turn, try to conquer most of South America by attacking Brazil and Peru, and having Peru surge to Argentina.
Now you want to watch out for orange in North America – he likes to come south and if he takes Brazil, the game will be much harder. I get insanely lucky and my 3 troops in Central America stop his 8 in the Eastern U.S. I now have complete control of South America.
The nice thing about this scenario is that it doesn’t matter who destroys the player who last owned Brazil. All I have to do now is to hang onto Brazil and wait until red dies.
Yellow defeats him and I have achieved victory.
If you are still having trouble with this level, I have written a few paragraphs that go more in-depth into strategy, and what has worked and not worked for me on this level. You can read that here.