See The Great Cause 1) cache page for the cartridge and the first set of instructions. You must have completed the tasks required for The Great Cause 3) in order to complete the tasks required for this cache.
In order to win the Battle of Bannockburn you first must have acquired 100 Kudos points in order to have gained sufficient support amongst the clans to raise an army. You then need to sneak into the English camp in Torwood to meet and extract Alexander Seton who will provide key information to tip the balance of the battle in the favour of Scotland. Once you have completed both of these tasks the location of the Battle of Bannockburn cache will appear on your map.
Details of how to acquire Kudos points are given in The Great Cause 3.
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