Iraq and Afghanistan aren't exactly at a 1700s level of technology or military training, either.
I'd expect the technological gap between a terrestrial civilization and an interstellar civilization to be far greater than 300 years. The reality is we have NO capability of retaliating against any space based weapon system outside of LEO - and even in low orbit a species that has mastered interstellar travel would likely have effectively impenetrable countermeasures for anything we could throw at them. If their goal is simply to wipe out life and harvest resources from our planet's carcass, there is absolutely nothing we could do to stop them. Even if the goal is to eliminate just the human population and leave a habitable planet, what would you propose we could do to stop precisely targeted kinetic strikes from an opponent in orbit?
Things get more interesting if the goal is to conquer or enslave the human population - that's a much closer analogy to Iraq and Afghanistan.