Index: binaries/data/mods/public/simulation/components/Garrisonable.js
===================================================================
--- binaries/data/mods/public/simulation/components/Garrisonable.js
+++ binaries/data/mods/public/simulation/components/Garrisonable.js
@@ -72,6 +72,10 @@
 
 	this.holder = entity;
 
+	let cmpUnitAI = Engine.QueryInterface(this.entity, IID_UnitAI);
+	if (cmpUnitAI)
+		cmpUnitAI.SetGarrisoned();
+
 	let cmpProductionQueue = Engine.QueryInterface(this.entity, IID_ProductionQueue);
 	if (cmpProductionQueue)
 		cmpProductionQueue.PauseProduction();
Index: binaries/data/mods/public/simulation/components/GuiInterface.js
===================================================================
--- binaries/data/mods/public/simulation/components/GuiInterface.js
+++ binaries/data/mods/public/simulation/components/GuiInterface.js
@@ -1857,7 +1857,7 @@
 GuiInterface.prototype.IdleUnitFilter = function(unit, idleClasses, excludeUnits)
 {
 	let cmpUnitAI = Engine.QueryInterface(unit, IID_UnitAI);
-	if (!cmpUnitAI || !cmpUnitAI.IsIdle() || cmpUnitAI.IsGarrisoned())
+	if (!cmpUnitAI || !cmpUnitAI.IsIdle() || cmpUnitAI.IsTurret())
 		return { "idle": false };
 
 	let cmpIdentity = Engine.QueryInterface(unit, IID_Identity);
Index: binaries/data/mods/public/simulation/components/Health.js
===================================================================
--- binaries/data/mods/public/simulation/components/Health.js
+++ binaries/data/mods/public/simulation/components/Health.js
@@ -134,7 +134,8 @@
 	if (this.GetIdleRegenRate() != 0)
 	{
 		let cmpUnitAI = Engine.QueryInterface(this.entity, IID_UnitAI);
-		if (cmpUnitAI && (cmpUnitAI.IsIdle() || cmpUnitAI.IsGarrisoned() && !cmpUnitAI.IsTurret()))
+		if (cmpUnitAI && (cmpUnitAI.IsIdle() ||
+			cmpUnitAI.GetGarrisonHolder() != INVALID_ENTITY && !cmpUnitAI.IsTurret()))
 			regen += this.GetIdleRegenRate();
 	}
 
Index: binaries/data/mods/public/simulation/components/UnitAI.js
===================================================================
--- binaries/data/mods/public/simulation/components/UnitAI.js
+++ binaries/data/mods/public/simulation/components/UnitAI.js
@@ -589,7 +589,7 @@
 			return ACCEPT_ORDER;
 		}
 
-		if (this.IsGarrisoned())
+		if (this.isGarrisoned)
 		{
 			this.SetNextState("INDIVIDUAL.GARRISON.GARRISONED");
 			return ACCEPT_ORDER;
@@ -610,8 +610,11 @@
 	},
 
 	"Order.Ungarrison": function() {
+		// Note that this order MUST succeed, or we break
+		// the assumptions done in garrisonable/garrisonHolder,
+		// especially in EjectOrKill in the latter.
+		// ToDo: This can be fixed by not making that assumption :)
 		this.FinishOrder();
-		this.isGarrisoned = false;
 		return ACCEPT_ORDER;
 	},
 
@@ -3259,9 +3262,6 @@
 							let cmpGarrisonable = Engine.QueryInterface(this.entity, IID_Garrisonable);
 							if (cmpGarrisonable.Garrison(target))
 							{
-								this.isGarrisoned = true;
-								this.SetImmobile(true);
-
 								if (this.formationController)
 								{
 									var cmpFormation = Engine.QueryInterface(this.formationController, IID_Formation);
@@ -3463,9 +3463,7 @@
 	this.orderQueue = []; // current order is at the front of the list
 	this.order = undefined; // always == this.orderQueue[0]
 	this.formationController = INVALID_ENTITY; // entity with IID_Formation that we belong to
-	this.isGarrisoned = false;
 	this.isIdle = false;
-	this.isImmobile = false; // True if the unit is currently unable to move (garrisoned,...)
 
 	this.heldPosition = undefined;
 
@@ -3539,14 +3537,11 @@
 	Engine.PostMessage(this.entity, MT_UnitIdleChanged, { "idle": this.isIdle });
 };
 
-UnitAI.prototype.IsGarrisoned = function()
-{
-	return this.isGarrisoned;
-};
-
 UnitAI.prototype.SetGarrisoned = function()
 {
+	// UnitAI caches its own garrisoned state for performance.
 	this.isGarrisoned = true;
+	this.SetImmobile();
 };
 
 UnitAI.prototype.GetGarrisonHolder = function()
@@ -3563,9 +3558,24 @@
 	return !this.orderQueue.length || this.orderQueue[0].type == "Garrison";
 };
 
-UnitAI.prototype.SetImmobile = function(immobile)
+UnitAI.prototype.SetImmobile = function()
+{
+	if (this.isImmobile)
+		return;
+
+	this.isImmobile = true;
+	Engine.PostMessage(this.entity, MT_UnitAbleToMoveChanged, {
+		"entity": this.entity,
+		"ableToMove": this.AbleToMove()
+	});
+};
+
+UnitAI.prototype.SetMobile = function()
 {
-	this.isImmobile = immobile;
+	if (!this.isImmobile)
+		return;
+
+	delete this.isImmobile;
 	Engine.PostMessage(this.entity, MT_UnitAbleToMoveChanged, {
 		"entity": this.entity,
 		"ableToMove": this.AbleToMove()
@@ -3888,7 +3898,7 @@
 	this.order = this.orderQueue[0];
 
 	let cmpPosition = Engine.QueryInterface(this.entity, IID_Position);
-	if (this.orderQueue.length && (this.IsGarrisoned() || this.IsFormationController() ||
+	if (this.orderQueue.length && (this.isGarrisoned || this.IsFormationController() ||
 	        cmpPosition && cmpPosition.IsInWorld()))
 	{
 		let ret = this.UnitFsm.ProcessMessage(this,
@@ -4063,7 +4073,7 @@
 			this.UpdateWorkOrders(type);
 	}
 
-	let garrisonHolder = this.IsGarrisoned() && type != "Ungarrison" ? this.GetGarrisonHolder() : null;
+	let garrisonHolder = this.isGarrisoned && type != "Ungarrison" ? this.GetGarrisonHolder() : null;
 
 	// Do not replace packing/unpacking unless it is cancel order.
 	// TODO: maybe a better way of doing this would be to use priority levels
@@ -4178,10 +4188,10 @@
 	if (this.workOrders.length == 0)
 		return false;
 
-	if (this.IsGarrisoned())
+	if (this.isGarrisoned)
 	{
-		let cmpGarrisonHolder = Engine.QueryInterface(this.GetGarrisonHolder(), IID_GarrisonHolder);
-		if (!cmpGarrisonHolder || !cmpGarrisonHolder.PerformEject([this.entity], false))
+		let cmpGarrisonable = Engine.QueryInterface(this.entity, IID_Garrisonable);
+		if (!cmpGarrisonable || !cmpGarrisonable.UnGarrison(false))
 			return false;
 	}
 
@@ -5362,7 +5372,7 @@
 	{
 		// May happen if an order arrives on the same turn the unit is garrisoned
 		// in that case, just forget the order as this will lead to an infinite loop
-		if (this.IsGarrisoned() && !this.IsTurret() && type != "Ungarrison")
+		if (this.isGarrisoned && !this.IsTurret() && type != "Ungarrison")
 			return;
 		this.ReplaceOrder(type, data);
 	}
@@ -5607,11 +5617,11 @@
  */
 UnitAI.prototype.Ungarrison = function()
 {
-	if (this.IsGarrisoned())
-	{
-		this.SetImmobile(false);
-		this.AddOrder("Ungarrison", null, false);
-	}
+	if (!this.isGarrisoned)
+		return;
+	delete this.isGarrisoned;
+	this.SetMobile();
+	this.AddOrder("Ungarrison", null, false);
 };
 
 /**
@@ -5619,7 +5629,6 @@
  */
 UnitAI.prototype.Autogarrison = function(target)
 {
-	this.isGarrisoned = true;
 	this.PushOrderFront("Garrison", { "target": target });
 };
 
Index: binaries/data/mods/public/simulation/helpers/Transform.js
===================================================================
--- binaries/data/mods/public/simulation/helpers/Transform.js
+++ binaries/data/mods/public/simulation/helpers/Transform.js
@@ -67,7 +67,7 @@
 			cmpNewUnitAI.SetHeldPosition(pos.x, pos.z);
 		if (cmpUnitAI.GetStanceName())
 			cmpNewUnitAI.SwitchToStance(cmpUnitAI.GetStanceName());
-		if (cmpUnitAI.IsGarrisoned())
+		if (cmpUnitAI.GetGarrisonHolder() != INVALID_ENTITY)
 			cmpNewUnitAI.SetGarrisoned();
 		cmpNewUnitAI.AddOrders(cmpUnitAI.GetOrders());
 		if (cmpUnitAI.IsGuardOf())