I finished a playthrough of ME3 yesterday, and when scanning the planet Illum, the people decided not to shoot at the capital ships, but at the troop transport ships delaying the reapers attack. Why can't we fire at the transport ships and the processing ships? Taking those out of the picture would really make life hard for the reapers to continue their harvest. The problem is we don't know how many of those ships the reapers have and how well guarded they are.
Because every time we get close enough to a Reaper they wipe out our fleets, which is why everyone is somehow hiding from the reapers. What's more, you do realise that the reapers didn't have tons and tons of pre-assimilated Baterians/asari/krogan/turians, right? They are evidently capable of harvesting any species (e.g. Baterians) without any ground support at all.
When the reapers are on the ground give Cains to the soldiers, not to fire at the reapers, but to fire at the ground the reapers are walking on. The ground would be unstable causing the reapers to fall over. I don't know if a reaper would be able to fly away if laying on its side or not but that few moments it would be vulnerable to attacks.
Reapers have engines capable of generating enough lift to counter gravity in a planet's atmosphere (else they couldn't ever lift off again) so this may work once; after that, the reapers will just hover while killing us or switch to bombarding us from orbit. And even if we could trip reapers, what next? We have been shown at every turn that all the combined fire from a fleet can't scratch their paint until we get lucky and hit a comic book weak spot.
Another is that the capital ships have a weak spot. Their joints near the bottom of their legs. This would be easy to do if the capital ships are isolated from each other like the two we see on Palavens moon. In the cutscene over Earth an Alliance ship fires to shots at a capital ship taking out two of its legs, of course a moment later the Alliance ship is destroyed.
Too bad no one in the alliance can aim - do you want to have marines in space suits floating 10ft from the weak spot with a targeting laser?
I think it was stated in the codex that continuous fire from 4 dreadnoughts was enough firepower to overcome a reaper capital ship's defenses, and a cruiser could take on a reaper destroyer with a bit of luck 1 on 1. these are from codex entries, so don't say i'm making this up simply to make an argument. I think if you've managed to completely bring the races together there should be enough firepower to give a conventional firefight a go. though it's also possible that the codex may be a propaganda tool, and the statements are not completely accurate.
There are 250+ reaper ships, which means we'd need about 1000 dreadnoughts to win assuming that the reapers will stand and fight despite knowing that they would get completely annihilated... Problem is that we have just 100. If the Reapers switch to guerrilla tactics (pick one base/homeworld/whatever at random, hit it with everything and flee before reinforcements can get there) we'd need more than 10000 (as every garrison would have to be large enough to fend of the entire reaper armada). That's just not gonna happen.
Hopelessness and gritty compromise are DEEP and ARTISTIC! If the protagonist doesn't heroically die to bring about a partial victory, then you just want rainbows and unicorns!
Stop trying to assume the galaxy has any hope or Shepard uniting the galaxy has any meaning
Why does cooperation only count if it's hitting the same guy?