diff --git a/scripts/verify-campaign-save-normalization.mjs b/scripts/verify-campaign-save-normalization.mjs
index 7de5484..5a1fc8c 100644
--- a/scripts/verify-campaign-save-normalization.mjs
+++ b/scripts/verify-campaign-save-normalization.mjs
@@ -596,6 +596,19 @@ try {
           reserveTraining: [],
           completedAt: '2026-07-04T02:00:00.000Z'
         },
+        'invalid-date-history-key': {
+          battleId: 'second-battle-yellow-turban-pursuit',
+          battleTitle: 'Invalid Date Battle',
+          outcome: 'victory',
+          rewardGold: 999,
+          itemRewards: [],
+          campaignRewards: { supplies: [], equipment: [], reputation: [], recruits: [], unlocks: [] },
+          objectives: [],
+          units: [],
+          bonds: [],
+          reserveTraining: [],
+          completedAt: 'not-a-date'
+        },
         corrupted: 'not-a-settlement'
       }
     })
@@ -654,7 +667,41 @@ try {
   const fallback = loadCampaignState();
   assert(fallback.step === 'second-camp' && fallback.activeSaveSlot === 2, `Expected valid slotted save fallback: ${JSON.stringify(fallback)}`);
 
-  console.log('Verified campaign save normalization, reward resettlement, camp reward idempotence, malformed-field/roster-equipment/bond-roster/report-reference/sortie-roster/latest-history/detail recovery, unknown-step/report/history recovery, unsupported-version rejection, and slotted fallback.');
+  storage.clear();
+  storage.set(campaignStorageKey, JSON.stringify({ version: 99, step: 'sixty-sixth-camp' }));
+  storage.set(
+    `${campaignStorageKey}:slot-1`,
+    JSON.stringify({
+      version: 1,
+      updatedAt: 'zzzz-latest-looking-corruption',
+      step: 'sixty-sixth-camp',
+      activeSaveSlot: 1,
+      gold: 999
+    })
+  );
+  storage.set(
+    `${campaignStorageKey}:slot-2`,
+    JSON.stringify({
+      version: 1,
+      updatedAt: '2026-07-02T00:00:00.000Z',
+      step: 'second-camp',
+      activeSaveSlot: 2,
+      gold: 260
+    })
+  );
+  const timestampSafeFallback = loadCampaignState();
+  assert(
+    timestampSafeFallback.step === 'second-camp' && timestampSafeFallback.activeSaveSlot === 2,
+    `Expected latest slotted fallback to ignore invalid timestamp saves: ${JSON.stringify(timestampSafeFallback)}`
+  );
+
+  const corruptedSlot = loadCampaignState(1);
+  assert(
+    !Number.isNaN(Date.parse(corruptedSlot.updatedAt)) && corruptedSlot.updatedAt !== 'zzzz-latest-looking-corruption',
+    `Expected explicitly loaded corrupted slot timestamp to be normalized: ${JSON.stringify(corruptedSlot)}`
+  );
+
+  console.log('Verified campaign save normalization, reward resettlement, camp reward idempotence, malformed-field/roster-equipment/bond-roster/report-reference/sortie-roster/latest-history/detail recovery, timestamp-safe history/slot recovery, unknown-step/report/history recovery, unsupported-version rejection, and slotted fallback.');
 } finally {
   await server.close();
 }
diff --git a/src/game/state/campaignState.ts b/src/game/state/campaignState.ts
index 17e2ab3..3cf76ed 100644
--- a/src/game/state/campaignState.ts
+++ b/src/game/state/campaignState.ts
@@ -831,7 +831,7 @@ function normalizeCampaignState(state: Partial<CampaignState>): CampaignState {
     ...cloneCampaignState(state as CampaignState)
   };
   normalized.version = 1;
-  normalized.updatedAt = typeof normalized.updatedAt === 'string' && normalized.updatedAt ? normalized.updatedAt : new Date().toISOString();
+  normalized.updatedAt = normalizeCampaignTimestamp(normalized.updatedAt) ?? new Date().toISOString();
   normalized.step = normalizeCampaignStep(normalized.step);
   normalized.activeSaveSlot = normalizeSlot(normalized.activeSaveSlot);
   normalized.gold = normalizeNonNegativeInteger(normalized.gold);
@@ -899,6 +899,23 @@ function normalizeNonNegativeInteger(value: unknown) {
   return Number.isFinite(numeric) && numeric > 0 ? numeric : 0;
 }
 
+function normalizeCampaignTimestamp(value: unknown) {
+  if (typeof value !== 'string' || value.length === 0) {
+    return undefined;
+  }
+
+  return campaignTimestampMs(value) === undefined ? undefined : value;
+}
+
+function campaignTimestampMs(value: unknown) {
+  if (typeof value !== 'string' || value.length === 0) {
+    return undefined;
+  }
+
+  const timestamp = Date.parse(value);
+  return Number.isFinite(timestamp) ? timestamp : undefined;
+}
+
 function normalizeInventory(value: unknown) {
   return Object.entries(recordOrEmpty(value)).reduce<Record<string, number>>((inventory, [itemId, amount]) => {
     const normalizedItemId = itemId.replace(/\s+/g, ' ').trim();
@@ -930,7 +947,7 @@ function normalizeLatestBattleId(value: unknown, battleHistory: Record<string, C
   }
 
   return Object.values(battleHistory)
-    .sort((a, b) => String(b.completedAt).localeCompare(String(a.completedAt)))[0]?.battleId;
+    .sort((a, b) => (campaignTimestampMs(b.completedAt) ?? 0) - (campaignTimestampMs(a.completedAt) ?? 0))[0]?.battleId;
 }
 
 function filterFirstBattleReportRosterReferences(report: FirstBattleReport, rosterUnitIds: Set<string>): FirstBattleReport {
@@ -951,14 +968,14 @@ function normalizeCampaignBattleSettlement(value: unknown): CampaignBattleSettle
 
   const settlement = value as Partial<CampaignBattleSettlement>;
   const battleId = typeof settlement.battleId === 'string' ? settlement.battleId : '';
+  const completedAt = normalizeCampaignTimestamp(settlement.completedAt);
   if (
     battleId.length === 0 ||
     !(battleId in battleScenarios) ||
     typeof settlement.battleTitle !== 'string' ||
     settlement.battleTitle.length === 0 ||
     (settlement.outcome !== 'victory' && settlement.outcome !== 'defeat') ||
-    typeof settlement.completedAt !== 'string' ||
-    settlement.completedAt.length === 0
+    !completedAt
   ) {
     return undefined;
   }
@@ -982,7 +999,7 @@ function normalizeCampaignBattleSettlement(value: unknown): CampaignBattleSettle
     reserveTraining: arrayOrEmpty<unknown>(settlement.reserveTraining)
       .map(normalizeReserveTrainingSnapshot)
       .filter((entry): entry is CampaignReserveTrainingSnapshot => Boolean(entry)),
-    completedAt: settlement.completedAt
+    completedAt
   };
 }
 
@@ -1154,7 +1171,7 @@ function normalizeFirstBattleReport(report: unknown): FirstBattleReport | undefi
     ),
     completedCampDialogues: uniqueStrings(report.completedCampDialogues),
     completedCampVisits: uniqueStrings(report.completedCampVisits),
-    createdAt: typeof report.createdAt === 'string' && report.createdAt.length > 0 ? report.createdAt : new Date().toISOString()
+    createdAt: normalizeCampaignTimestamp(report.createdAt) ?? new Date().toISOString()
   };
 }
 
@@ -1276,6 +1293,11 @@ function reserveTrainingFocusDefinition(focusId?: string) {
 }
 
 function readStoredCampaignState(slot?: number) {
+  const parsed = readStoredCampaignStateObject(slot);
+  return parsed ? normalizeCampaignState(parsed) : undefined;
+}
+
+function readStoredCampaignStateObject(slot?: number) {
   const raw = tryStorage()?.getItem(slot ? campaignSaveSlotKey(slot) : campaignStorageKey);
   if (!raw) {
     return undefined;
@@ -1289,7 +1311,7 @@ function readStoredCampaignState(slot?: number) {
     if (parsed.version !== undefined && parsed.version !== 1) {
       return undefined;
     }
-    return normalizeCampaignState(parsed);
+    return parsed;
   } catch {
     return undefined;
   }
@@ -1320,10 +1342,18 @@ function normalizeSlot(slot: number | undefined) {
 }
 
 function readLatestSlottedCampaignState() {
-  const latest = listCampaignSaveSlots()
-    .filter((slot) => slot.exists && slot.updatedAt)
-    .sort((a, b) => String(b.updatedAt).localeCompare(String(a.updatedAt)))[0];
-  return latest ? readStoredCampaignState(latest.slot) : undefined;
+  let latestSlot: number | undefined;
+  let latestUpdatedAt = Number.NEGATIVE_INFINITY;
+
+  for (let slot = 1; slot <= campaignSaveSlotCount; slot += 1) {
+    const timestamp = campaignTimestampMs(readStoredCampaignStateObject(slot)?.updatedAt);
+    if (timestamp !== undefined && timestamp > latestUpdatedAt) {
+      latestSlot = slot;
+      latestUpdatedAt = timestamp;
+    }
+  }
+
+  return latestSlot ? readStoredCampaignState(latestSlot) : undefined;
 }
 
 function advanceBond(bond: CampBondSnapshot, amount: number) {