diff --git a/services/api/src/matches/scenarios.rs b/services/api/src/matches/scenarios.rs
index 66c4ff2..149eb04 100644
--- a/services/api/src/matches/scenarios.rs
+++ b/services/api/src/matches/scenarios.rs
@@ -244,6 +244,22 @@ mod tests {
         assert_eq!(steiner.deploy, "E");
     }
 
+    /// Nobody deploys "Any". Upstream leaves the two defending forces without
+    /// a zone, which is a tabletop instruction - the defender places them -
+    /// and becomes "scatter across the whole three-map board" once MegaMek is
+    /// doing the placing, up to and including inside an attacker's own zone.
+    #[test]
+    fn every_monte_diablo_force_has_a_zone() {
+        let monte = find("MonteDiablo/MonteDiablo-Four_Players.mms").unwrap();
+        for slot in &monte.slots {
+            assert_ne!(
+                slot.deploy, "Any",
+                "{} deploys anywhere, including on top of somebody else",
+                slot.name
+            );
+        }
+    }
+
     /// A team is only claimed when the file says so, and Monte Diablo now
     /// says so: upstream declared none, which made it a four-way free-for-all
     /// with the 2nd and 7th Donegal Guards shooting at each other, and the
diff --git a/services/api/src/matches/scenarios/MonteDiablo/MonteDiablo-Four_Players.mms b/services/api/src/matches/scenarios/MonteDiablo/MonteDiablo-Four_Players.mms
index 8d5b64f..9b79351 100644
--- a/services/api/src/matches/scenarios/MonteDiablo/MonteDiablo-Four_Players.mms
+++ b/services/api/src/matches/scenarios/MonteDiablo/MonteDiablo-Four_Players.mms
@@ -25,8 +25,19 @@ Maps=Map Set 2/16x17 BattleTech,Map Set 5/16x17 Large Mountain 1,scenarios/opent
 Factions=Steiner2nd,Steiner7th,Davion,ComStar
 Location_Steiner7th=W
 Location_Steiner2nd=E
-Location_Davion=Any
-Location_ComStar=Any
+# lance.blue: the defenders hold the middle.
+#
+# Upstream gives both of them `Any`, which on a tabletop means the defender
+# sets up wherever they like. MegaMek deploys them for us instead, and `Any`
+# there is the whole three-map board - so the Lancers and the 167th scatter
+# across it and can land inside a Steiner deployment zone, which is not a
+# fight anybody set up.
+#
+# CTR because the Guards converge *in on* them: the 7th from the west and the
+# 2nd from the east, onto the headquarters company between the two. That is
+# the shape the Description states and the one the battle had.
+Location_Davion=CTR
+Location_ComStar=CTR
 
 # lance.blue: the two Donegal Guards commands fight as one side.
 #