DateListPlot version

DateListPlot[data, Joined -> False, 
 FrameTicks -> {{None, tickLabels}, {Automatic, None}}]

ordinalScale = 
  AssociationThread[{"Confederate victory", "Inconclusive", 
     "Union strategic victory", "Union victory", 
     "Decisive Union victory"} -> {-1, 0, 1, 2, 3}];
tickLabels = KeyValueMap[List /* Reverse, ordinalScale];
topOutcomes = Query[
    DeleteMissing /* KeySortBy[DateObject[#["StartDate"], "Day"] &],
    First /* (ordinalScale@# &)
    ]@EntityValue[UlyssesSGrantBattles, "OutcomeNotes", 
    "EntityAssociation"];
battleDates = KeyMap[DateObject[#["StartDate"], "Day"] &, topOutcomes];
data = Rule[TimeSeries[battleDates], Keys[topOutcomes]];