diff --git a/MultiversalDiplomacy/Adjudicate/Decision/MovementDecisions.cs b/MultiversalDiplomacy/Adjudicate/Decision/MovementDecisions.cs
index 36c4ced..5002093 100644
--- a/MultiversalDiplomacy/Adjudicate/Decision/MovementDecisions.cs
+++ b/MultiversalDiplomacy/Adjudicate/Decision/MovementDecisions.cs
@@ -13,7 +13,7 @@ public class MovementDecisions
     public Dictionary<MoveOrder, DefendStrength> DefendStrength { get; }
     public Dictionary<MoveOrder, PreventStrength> PreventStrength { get; }
     public Dictionary<MoveOrder, DoesMove> DoesMove { get; }
-    public Dictionary<Season, AdvanceTimeline> AdvanceTimeline { get; }
+    public Dictionary<string, AdvanceTimeline> AdvanceTimeline { get; }
 
     public IEnumerable<AdjudicationDecision> Values =>
         IsDislodged.Values.Cast<AdjudicationDecision>()
@@ -47,7 +47,7 @@ public class MovementDecisions
         var submittedOrdersBySeason = orders.Cast<UnitOrder>().ToLookup(order => order.Unit.Season);
         foreach (var group in submittedOrdersBySeason)
         {
-            AdvanceTimeline[group.Key] = new(group.Key, group);
+            AdvanceTimeline[group.Key.Designation] = new(group.Key, group);
         }
 
         // Create timeline decisions for each season potentially affected by the submitted orders.
@@ -60,27 +60,27 @@ public class MovementDecisions
             {
                 case MoveOrder move:
                     AdvanceTimeline.Ensure(
-                        world.Seasons[move.Season],
+                        move.Season,
                         () => new(world.Seasons[move.Season], world.OrderHistory[move.Season].Orders));
-                    AdvanceTimeline[world.Seasons[move.Season]].Orders.Add(move);
+                    AdvanceTimeline[move.Season].Orders.Add(move);
                     break;
 
                 case SupportHoldOrder supportHold:
                     AdvanceTimeline.Ensure(
-                        supportHold.Target.Season,
+                        supportHold.Target.Season.Designation,
                         () => new(supportHold.Target.Season, world.OrderHistory[supportHold.Target.Season.Designation].Orders));
-                    AdvanceTimeline[supportHold.Target.Season].Orders.Add(supportHold);
+                    AdvanceTimeline[supportHold.Target.Season.Designation].Orders.Add(supportHold);
                     break;
 
                 case SupportMoveOrder supportMove:
                     AdvanceTimeline.Ensure(
-                        supportMove.Target.Season,
+                        supportMove.Target.Season.Designation,
                         () => new(supportMove.Target.Season, world.OrderHistory[supportMove.Target.Season.Designation].Orders));
-                    AdvanceTimeline[supportMove.Target.Season].Orders.Add(supportMove);
+                    AdvanceTimeline[supportMove.Target.Season.Designation].Orders.Add(supportMove);
                     AdvanceTimeline.Ensure(
-                        supportMove.Season,
+                        supportMove.Season.Designation,
                         () => new(supportMove.Season, world.OrderHistory[supportMove.Season.Designation].Orders));
-                    AdvanceTimeline[supportMove.Season].Orders.Add(supportMove);
+                    AdvanceTimeline[supportMove.Season.Designation].Orders.Add(supportMove);
                     break;
             }
         }