Wiki systems typically display article history as a linear sequence of revisions in chronological order. This presentation hides deeper relationships among the revisions, such as which earlier revision provided most of the content for a later revision, or when a revision effectively reverses the changes made by a prior revision. These relationships are valuable in understanding what happened between editors in conflict over article content. We present methods for detecting when a revision discards the work of one or more other revisions, a means of visualizing these relationships in-line with existing history views, and a computational method for detecting discarded work. We show through a series of examples that these tools can aid mediators of wiki content disputes by making salient the structure of the ongoing conflict. Further, the computational tools provide a means of determining whether or not a revision has been accepted by the community of editors surrounding the article.