A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
For the purposes of cards like Seeking the Truth:
Player A attacks me, with one 4F personality.
I defend, and upon Engagement play "Seeking the Truth" for Siege Volley, which I then use to destroy the 4F Personality as a battle action.
He passes, and then I pass.
Since I have destroyed the last unit in the army have I "destroyed an army" for the purposes of Seeking the Truth?
More generally, is the phrase "destroying an army" limited to Battle Resolution only?
Yes, as the only place in the rules you'll find the reference to destroying an army is the CR for Battle resolution, removing an opponent's army via battle actions will not satisfy the requirement on Seeking the Truth.