diff --git a/src/board/OasisRegion.svelte b/src/board/OasisRegion.svelte
index 5c65b6f..f1bf970 100644
--- a/src/board/OasisRegion.svelte
+++ b/src/board/OasisRegion.svelte
@@ -1,7 +1,27 @@
 <script lang="ts">
+    import moves from "../moves";
     import type { OasisType } from "../types";
+    import { getRemainingUnitCount } from "../utils";
+    import village from "../village";
 
     export let region: OasisType;
+
+
+    let numberOfUnits = 0;
+    $: maximumUnits = getRemainingUnitCount($village, 'soldier');
+    $: if (numberOfUnits > maximumUnits) {
+        numberOfUnits = maximumUnits || 0;
+    }
+
+
+    function setMaxUnits() {
+        numberOfUnits = maximumUnits;
+    }
+
+
+    function pillage() {
+        moves.pillage(region.state.index, numberOfUnits);
+    }
 </script>
 
 <div>
@@ -10,10 +30,31 @@
         Oasis
         (→ { region.distance })
     </h2>
+    { #if region.state.mission }
     <div>
-        <button>Pillage</button>
-        <button>Conquer</button>
+        <p>{ region.state.mission.unitCount } soldiers are on a mission here.</p>
+        <p>Remaining: { Math.ceil(region.state.mission.remainingTime / 1000) }</p>
     </div>
+    { :else }
+    <div>
+        <input
+            type="range"
+            name="units"
+            min="0"
+            max={ maximumUnits }
+            bind:value={ numberOfUnits }
+        />
+        <input
+            type="number"
+            name="units"
+            min="0"
+            max={ maximumUnits }
+            bind:value={ numberOfUnits }
+        />
+        <button on:click={ setMaxUnits }>↑</button>
+        <button on:click={ pillage } disabled={ numberOfUnits === 0 }>Pillage</button>
+    </div>
+    { /if }
 </div>
 
 <style>
diff --git a/src/hud/Units.svelte b/src/hud/Units.svelte
index 9ac07e7..a9a9b73 100644
--- a/src/hud/Units.svelte
+++ b/src/hud/Units.svelte
@@ -1,5 +1,6 @@
 <script lang="ts">
     import units from "../data/units";
+    import { getRemainingUnitCount } from "../utils";
     import village from "../village";
 
     $: currentUnits = Object.entries($village.units).map(([type, count]) => {
@@ -17,6 +18,6 @@
 
 <section>
     { #each currentUnits as unit }
-    <p>{ unit.name }: { unit.count }</p>
+    <p>{ unit.name }: { getRemainingUnitCount($village, unit.type) } / { unit.count }</p>
     { /each }
 </section>
diff --git a/src/missions.ts b/src/missions.ts
new file mode 100644
index 0000000..f38ee36
--- /dev/null
+++ b/src/missions.ts
@@ -0,0 +1,31 @@
+import type { OasisType, RegionType } from "./types";
+import type { VillageState } from "./village";
+
+
+export function resolveMission(V: VillageState, region: RegionType) {
+    const mission = region.state.mission;
+    if (!mission) {
+        return;
+    }
+
+    switch (mission.type) {
+        case 'pillage':
+            if (region.type === 'oasis') {
+                resolvePillageOasis(V, region);
+            }
+            break;
+        default:
+            throw new Error(`Unknown mission type: "${ mission.type }"`);
+    }
+}
+
+
+function resolvePillageOasis(V: VillageState, region: OasisType) {
+    const mission = region.state.mission;
+    if (!mission) {
+        return;
+    }
+
+    V.resources[region.resource] += mission.unitCount * 40;
+    delete region.state.mission;
+}
diff --git a/src/moves/index.ts b/src/moves/index.ts
index c7350e1..25d916f 100644
--- a/src/moves/index.ts
+++ b/src/moves/index.ts
@@ -4,6 +4,7 @@ import village, { type VillageState } from '../village';
 import build from './build';
 import upgradeBuilding from './upgradeBuilding';
 import recruitUnits from './recruitUnits';
+import pillage from './pillage';
 
 
 // Encapsulates a move function into a store update, where the data is made
@@ -31,5 +32,6 @@ export function makeMove(move: (...args: any[]) => boolean) {
 export default {
     build: makeMove(build),
     upgradeBuilding: makeMove(upgradeBuilding),
+    pillage: makeMove(pillage),
     recruitUnits: makeMove(recruitUnits),
 };
diff --git a/src/moves/pillage.ts b/src/moves/pillage.ts
new file mode 100644
index 0000000..4a309ee
--- /dev/null
+++ b/src/moves/pillage.ts
@@ -0,0 +1,24 @@
+import { getRemainingUnitCount } from "../utils";
+import type { VillageState } from "../village";
+
+
+export default function pillage(V: VillageState, regionIndex: number, soldiersCount: number) {
+    if (soldiersCount > getRemainingUnitCount(V, 'soldier')) {
+        return false;
+    }
+
+    const region = V.worldmap[regionIndex];
+
+    if (region.state.mission) {
+        return false;
+    }
+
+    region.state.mission = {
+        type: 'pillage',
+        unitType: 'soldier',
+        unitCount: soldiersCount,
+        remainingTime: region.distance * 10 * 1000,
+    };
+
+    return true;
+}
diff --git a/src/types.ts b/src/types.ts
index 00356e0..ef137e9 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -64,12 +64,18 @@ export interface UnitType {
 }
 
 
+export interface MissionType {
+    type: string;
+    unitType: string;
+    unitCount: number;
+    remainingTime: number;
+}
+
 interface BaseRegionType {
     distance: number;
     state: {
-        mission?: {
-            type: string;
-        };
+        index: number;
+        mission?: MissionType;
     };
 }
 
diff --git a/src/update.ts b/src/update.ts
index 544ad4b..c00fdbe 100644
--- a/src/update.ts
+++ b/src/update.ts
@@ -1,6 +1,7 @@
 import { produce } from 'immer';
 
 import { CULTURE_TO_WIN } from './constants';
+import { resolveMission } from './missions';
 import type { ProductionType } from './types';
 import { getProduction, getStorage, shuffle } from './utils';
 import village, { type VillageState } from "./village";
@@ -32,6 +33,19 @@ export default function update(timestamp: number) {
                 }
             });
 
+            // Advance missions.
+            V.worldmap.forEach(region => {
+                if (!region.state.mission) {
+                    return;
+                }
+
+                const mission = region.state.mission;
+                mission.remainingTime -= delta;
+                if (mission.remainingTime <= 0) {
+                    resolveMission(V, region);
+                }
+            });
+
             // Make all buildings and units produce and consume.
             const productionPerMinute = getProduction(V);
             const storage = getStorage(V);
diff --git a/src/utils.ts b/src/utils.ts
index eb93360..814b27a 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,5 +1,5 @@
 import units from "./data/units";
-import type { BuildingType, CostType, ProductionType, ResourcesType } from "./types";
+import type { BuildingType, CostType, MissionType, ProductionType, ResourcesType } from "./types";
 import type { VillageState } from "./village";
 
 
@@ -88,6 +88,14 @@ export function getUnitSource(unitType: string) {
 }
 
 
+export function getRemainingUnitCount(V: VillageState, unitType: string) {
+    let total = V.units[unitType] || 0;
+    const missions = V.worldmap.filter(r => r.state.mission?.unitType === unitType).map(r => r.state.mission);
+    missions.forEach(m => total -= m?.unitCount || 0);
+    return total;
+}
+
+
 export function getKeysAsNumbers(dict: Object): Array<number> {
     return Object.keys(dict).map(i => parseInt(i)).sort((a, b) => a - b);
 }
diff --git a/src/village.ts b/src/village.ts
index 3664d9d..fc5ad2d 100644
--- a/src/village.ts
+++ b/src/village.ts
@@ -66,11 +66,13 @@ function getInitialOutsideBoard() {
 
 
 function getInitialWorldmap(): RegionType[] {
-    return worldmap.map(r => {
+    return worldmap.map((r, index) => {
         const region = r as RegionType;
         return {
             ...region,
-            state: {},
+            state: {
+                index,
+            },
         };
     });
 }