All battlefield quests are random. All involve either finding a certain item lying on the floor or a certain enemy to kill. All of these encounters are found on the bottem levels (level 3) of the dungeon.
Either you didn't fully explore each of the three bottem levels in act 1 or there was a bug (the random generator for the bottem level is a bit buggy). The rewards are small so you can just move along - the quests will be removed from your book as soon as act 2 starts.
