diff --git a/scripts/verify-campaign-save-normalization.mjs b/scripts/verify-campaign-save-normalization.mjs
index 24e3aa1..7de5484 100644
--- a/scripts/verify-campaign-save-normalization.mjs
+++ b/scripts/verify-campaign-save-normalization.mjs
@@ -494,6 +494,37 @@ try {
     `Expected malformed report fields to be normalized without discarding the report: ${JSON.stringify(malformedReport)}`
   );
 
+  storage.clear();
+  storage.set(
+    campaignStorageKey,
+    JSON.stringify({
+      version: 1,
+      updatedAt: '2026-07-04T00:30:00.000Z',
+      step: 'fourth-camp',
+      firstBattleReport: {
+        battleId: 'unknown-battle-id',
+        battleTitle: 'Unknown Battle',
+        outcome: 'victory',
+        turnNumber: 4,
+        rewardGold: 120,
+        defeatedEnemies: 3,
+        totalEnemies: 5,
+        objectives: [],
+        units: [],
+        bonds: [],
+        itemRewards: [],
+        completedCampDialogues: [],
+        completedCampVisits: [],
+        createdAt: '2026-07-04T00:30:00.000Z'
+      }
+    })
+  );
+  const unknownReport = loadCampaignState();
+  assert(
+    unknownReport.step === 'fourth-camp' && unknownReport.firstBattleReport === undefined,
+    `Expected first battle report with unknown battle id to be discarded safely: ${JSON.stringify(unknownReport)}`
+  );
+
   storage.clear();
   storage.set(
     campaignStorageKey,
@@ -552,6 +583,19 @@ try {
           ],
           completedAt: '2026-07-04T01:00:00.000Z'
         },
+        'unknown-battle-key': {
+          battleId: 'unknown-battle-id',
+          battleTitle: 'Unknown Battle',
+          outcome: 'victory',
+          rewardGold: 999,
+          itemRewards: [],
+          campaignRewards: { supplies: [], equipment: [], reputation: [], recruits: [], unlocks: [] },
+          objectives: [],
+          units: [],
+          bonds: [],
+          reserveTraining: [],
+          completedAt: '2026-07-04T02:00:00.000Z'
+        },
         corrupted: 'not-a-settlement'
       }
     })
diff --git a/src/game/state/campaignState.ts b/src/game/state/campaignState.ts
index b1b5c28..17e2ab3 100644
--- a/src/game/state/campaignState.ts
+++ b/src/game/state/campaignState.ts
@@ -950,9 +950,10 @@ function normalizeCampaignBattleSettlement(value: unknown): CampaignBattleSettle
   }
 
   const settlement = value as Partial<CampaignBattleSettlement>;
+  const battleId = typeof settlement.battleId === 'string' ? settlement.battleId : '';
   if (
-    typeof settlement.battleId !== 'string' ||
-    settlement.battleId.length === 0 ||
+    battleId.length === 0 ||
+    !(battleId in battleScenarios) ||
     typeof settlement.battleTitle !== 'string' ||
     settlement.battleTitle.length === 0 ||
     (settlement.outcome !== 'victory' && settlement.outcome !== 'defeat') ||
@@ -963,7 +964,7 @@ function normalizeCampaignBattleSettlement(value: unknown): CampaignBattleSettle
   }
 
   return {
-    battleId: settlement.battleId,
+    battleId,
     battleTitle: settlement.battleTitle,
     outcome: settlement.outcome,
     rewardGold: normalizeNonNegativeInteger(settlement.rewardGold),
@@ -1112,9 +1113,10 @@ function normalizeFirstBattleReport(report: unknown): FirstBattleReport | undefi
     return undefined;
   }
 
+  const battleId = typeof report.battleId === 'string' ? report.battleId : '';
   if (
-    typeof report.battleId !== 'string' ||
-    report.battleId.length === 0 ||
+    battleId.length === 0 ||
+    !(battleId in battleScenarios) ||
     (report.outcome !== 'victory' && report.outcome !== 'defeat')
   ) {
     return undefined;
@@ -1123,13 +1125,13 @@ function normalizeFirstBattleReport(report: unknown): FirstBattleReport | undefi
   const battleTitle =
     typeof report.battleTitle === 'string' && report.battleTitle.length > 0
       ? report.battleTitle
-      : battleScenarios[report.battleId as BattleScenarioId]?.title;
+      : battleScenarios[battleId as BattleScenarioId]?.title;
   if (!battleTitle) {
     return undefined;
   }
 
   return {
-    battleId: report.battleId,
+    battleId,
     battleTitle,
     outcome: report.outcome,
     turnNumber: normalizeNonNegativeInteger(report.turnNumber),