[HoneyBadger]

Ok, first of all, everyone's copying Adept's comment on Atom bombs, and labeling it as mine.
He wrote the comment about 1945, not me, so he deserves the credit.

Second of all, a species technologically advanced enough to cross the gulf of stars, and willing to spend the unimaginable resources it would take to invade a planet, would likely be smart enough to have an immune system that could defeat our diseases. They probably wouldn't even use a natural immune system, they'd have nanobots, or something even better, filling that role. So our diseases would have about as much chance as monkey PD does against fully equipped Niefel Jarls-if those Niefel Jarls were made of solid tungsten carbide, and shot lazer beams from their eyes.

Ofcourse, if it were me planning the invasion, I wouldn't send any of my own people there until my vast robot armies had dealt with most of the resistance.

Third, I've seen the original movie-Tom Cruise is in the remake, so I haven't bothered with the newer version yet-and I've even read the book, a long, long time ago, when I was in elementary school.