What was AVALANCHE doing immediately prior to the start of the game? I don't recall if we're ever made privy to this. Talking to Biggs and Jessie as you enter the reactor yields comments about AVALANCHE operatives who gave their lives to obtain the codes to break in, so there was clearly some espionage going on there. But the Mako Reactor No. 1 is the first one they assault.

So what do you think AVALANCHE was doing before that to be able to call themselves an "anti-Shinra" group? They seem relatively well organised too, which means this wasn't just a slapped together haphazard plan. AVALANCHE is one of the most mysterious rebel groups we ever encounter in Final Fantasy.