There's a real difference on "lets murder some randons" and "let's get in war against said faction", as there's a difference on "lets group up and break this guy we don't like house door, get in, spank him to death, rob everything and get out" and "lets go on war against X country". The first one don't requiere you much preparation, just a plan to pass by the defenses and get your victm unaware of the situation untill you hit. The second case requires TONS of preparation, time, and both sides knowing what's going on (a war damn).
If you want to quiclky raid, FIND YOUR WAY, as many have found (some may have found illegal ways

Main problem I see here is ppl confusing a 5 guys group with an army, and street fights with war!