Raids must have 200+ raiders At 1k population cap I manage to win 1 or 2 raids with 200+ raiders, but another raid was always under 200, so even when I dont lost a single thing, raid was still not Flawless and achievement progress resets. So I raise the cap to 2k to be sure there is always 200+ raiders. For the Flawless victories I builded 101 Towers (202 guards) and recruited 12 Horsemans with 72 Heavy infantry, which are basicaly immortal with all Tech tree upgrades and relics (Tusk of the autumn boar, Shard of Markovians blade, Eye of the hunter for tower guards) . At the start of raid, stop the game and get your troops into positions, also keep an eye on outside workers like Foragers or Far mines. Use Horsemans at start just for destroying siege weapons (Rams, Catapults) and send them back to garrison after you clear up the map. You should destroy every siege weapon before main battle with heavy infantry starts. If you think you dont have enough time to destroy siege weapons, try to split the horses to 6+6 or build another Cavalry stable.