Index: binaries/data/mods/public/gui/session/selection_details.js
===================================================================
--- binaries/data/mods/public/gui/session/selection_details.js
+++ binaries/data/mods/public/gui/session/selection_details.js
@@ -80,9 +80,10 @@
 	// Rank
 	if (entState.identity && entState.identity.rank && entState.identity.classes)
 	{
+		const rankObj = GetTechnologyData(entState.identity.rankTechName, playerState.civ);
 		Engine.GetGUIObjectByName("rankIcon").tooltip = sprintf(translate("%(rank)s Rank"), {
 			"rank": translateWithContext("Rank", entState.identity.rank)
-		});
+		}) + (rankObj ? "\n" + rankObj.tooltip : "");
 		Engine.GetGUIObjectByName("rankIcon").sprite = "stretched:session/icons/ranks/" + entState.identity.rank + ".png";
 		Engine.GetGUIObjectByName("rankIcon").hidden = false;
 	}
Index: binaries/data/mods/public/gui/session/session.js
===================================================================
--- binaries/data/mods/public/gui/session/session.js
+++ binaries/data/mods/public/gui/session/session.js
@@ -234,7 +234,10 @@
 
 	if (!(technologyName in g_TechnologyData[civ]))
 	{
-		let template = GetTechnologyDataHelper(TechnologyTemplates.Get(technologyName), civ, g_ResourceData);
+		const tech = TechnologyTemplates.Get(technologyName);
+		if (!tech)
+			return;
+		let template = GetTechnologyDataHelper(tech, civ, g_ResourceData);
 		translateObjectKeys(template, ["specific", "generic", "description", "tooltip", "requirementsTooltip"]);
 		g_TechnologyData[civ][technologyName] = deepfreeze(template);
 	}
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
@@ -273,6 +273,7 @@
 	if (cmpIdentity)
 		ret.identity = {
 			"rank": cmpIdentity.GetRank(),
+			"rankTechName": cmpIdentity.GetRankTechName(),
 			"classes": cmpIdentity.GetClassesList(),
 			"selectionGroupName": cmpIdentity.GetSelectionGroupName(),
 			"canDelete": !cmpIdentity.IsUndeletable(),
Index: binaries/data/mods/public/simulation/components/Identity.js
===================================================================
--- binaries/data/mods/public/simulation/components/Identity.js
+++ binaries/data/mods/public/simulation/components/Identity.js
@@ -149,6 +149,11 @@
 	return this.template.Rank || "";
 };
 
+Identity.prototype.GetRankTechName = function()
+{
+	return this.template.Rank ? "unit_" + this.template.Rank.toLowerCase() : "";
+};
+
 Identity.prototype.GetClassesList = function()
 {
 	return this.classesList;