[quote=catchamber]
How would this interstellar invasion fare against lasers?
[/quote]

Truth be told, outside of science fiction, lasers are really NOT very good weapons for space warfare.

While they lack a lag over a distance of about 1 light-second, they also have to put a LOT more energy into doing damage than a kinetic weapon, moreover they're going to heat your ship up fast, unless you have vast (and easily destroyed) radiators, by the time you've expended enough energy to actually kill an enemy ship you've boiled your crew.

Indeed. Kinetic weapons are some of the most powerful in space. 

If you shoot a 10 ton projectile at, say, .2c then it'll have gigatons of kinetic energy released when it hits the target. Fire it at about .6-.9c and then your projectile's destructive potential is equal to its weight in antimatter.