Z Route: Redemption Soldier Promotion and Upgrade Guide

To upgrade soldiers in Z Route: Redemption, open your barracks, select an existing lower-tier reserve unit, and select the promotion command. Upgrading converts older units into your highest unlocked tier for that unit type. Instead of paying the full recruitment price and timer, you pay only the difference in resources and training time between the unit's current tier and the target tier.

How Troop Promotion Works

Troop promotion converts existing lower-tier units rather than creating additional soldiers. When you recruit fresh units, you pay their full baseline cost in resources—such as food, iron, and coin—and wait through the full training timer. When you promote a unit:

• Resource Costs: The game charges only the differential cost between the soldier's current tier and the newly targeted tier.
• Training Time: The barracks queue timer reflects only the time gap between tiers, finishing significantly faster than a full recruitment cycle.
• Army Size: Total troop headcount remains unchanged because existing units are transformed rather than added.

This mechanism ensures that resources and time spent on early-game recruitment are not lost when higher tiers become available.

Promoting vs. Fresh Training

Choosing whether to promote or train depends on your current drill ground capacity and upcoming needs.

Train fresh troops when your drill grounds are underfilled or after suffering heavy permanent casualties. Use promotion once your army capacity is full, replacing obsolete tiers with your strongest unlocked forces.

Requirements to Unlock Higher Soldier Tiers

You cannot promote soldiers to a tier you have not yet unlocked. Upgrading your roster requires synchronizing three base facilities:

1. Headquarters and Barracks Milestones: Each soldier tier requires reaching specific barracks building levels. If barracks upgrades lag behind your headquarters, higher-tier promotions remain locked.
2. Institute Military Research: Advancing to new unit tiers requires completing prerequisite research nodes in the military branch of the institute.
3. Drill Ground Capacity: While promoting existing units does not consume additional housing space, keeping drill grounds upgraded ensures your base can hold new troops gained from mission rewards alongside your active reserves.

Best Timing for Large-Scale Promotions

Because barracks cannot recruit new troops while a promotion queue is active, plan large upgrades around your operational schedule:

• Event Point Milestones: Save mass promotions for server events that award points for power gains or speedup usage. Because promotion timers are short per unit, you can cycle through large batches and reach event milestones faster than through standard training.
• Pre-War Mobilization: Keep a reserve of lower-tier units ready to promote immediately before major alliance warfare or capital defense operations. This allows you to scale up squad power on short notice without cluttering barracks queues during active combat.

Squad Balance and Hospital Space

Deploying mixed-tier units in the same march weakens combat performance. Lower-tier soldiers have inferior defensive statistics, causing them to take heavy damage and fill hospital beds quickly when hit by area-of-effect attacks.

• Promote Legacy Rewards: Story missions and map exploration frequently reward low-tier troop bundles. Promote these legacy units immediately before assigning them to active marches.
• Prioritize Primary Marches: Assign your highest-tier units to your primary hero squad to maximize frontline survivability and damage output.
• Protect Hospital Capacity: Wounded units occupy hospital beds regardless of tier. Keeping your roster fully promoted ensures that any troops taking up hospital capacity return to service as maximum-tier combatants.