PrerequisitesIn order you build your Third City, you must prove your worth by gathering 4 Sir Bor's Crests, 2 Sir Ector's Crests, and 1 Sir Kay's Crest.
Once you have acquired these crests you will Earn Your Third City Quest and gain your Third City Deed. If you wish to speed up the process, you may buy the Squire's Chest in the Chest section of the Shop to fulfill a portion of your Crest needs. It may take multiple Squire’s Chests to earn the crests you need. Once purchased, the Chest will appear in My Items under Chest.
Once you have collected all required crests, Check Quests to obtain your Third City Deed. After fulfilling the 3th City Deed Quest, all crests needed for that quest will disappear. The deed will be located in My Items under Court.
You do not have to conquer it, only be victorious in the battle. These Crests will not always be rewarded, but only when Arthur takes note of your achievement. (When defeating a Wilderness there is only a percentage chance of a Crest drop.)
Higher levels of wilderness have greater chances of winning crests. Bors crests are easier to get than Ectors, and Bors and Ectors are both easier to get than Kay's.
See Crest_Drop_Research for more information on crest dropping. That is, the frequency and location of crest finds.