Whiteout Survival Fortress Battles Guide [2026] — Complete Walkthrough

Fortress Battles is weekly alliance PvP content fought across Fortresses and Strongholds on the World Map. This guide covers the event's structure, registration rules, occupation mechanics, reward systems, and the strategic implications of each.

Overview

Fortress Battles is a recurring alliance PvP event in which alliances across the State compete to occupy and hold buildings on the World Map. Buildings come in two types — Fortresses and Strongholds — and the event runs in seasonal cycles. Each season is reported to span 8 weeks, with one battle phase per week.

Holdings carry forward within a season: an alliance that occupies a building in one phase is automatically registered to defend it in the next phase of the same season. At season's end, holdings reset, and the first phase of a new season requires fresh registration even for buildings held at the close of the previous one. This carryover-then-reset structure shapes the strategic arc of a season — alliances accumulate defensive obligations across the season, then start clean again.

Unlocking the Event

Fortress Battles becomes available based on server progression rather than at a fixed calendar date, and unlock timing varies between servers. Fortresses become contestable before Strongholds; on most servers, Fortresses unlock during the early server window and Strongholds follow several weeks later.

In a server's first Fortress Battles season, only Fortresses are contestable initially. Strongholds typically enter the event around the fourth week of the first season, though exact timing is server-dependent. On mature servers running their second or later season, all 16 buildings are contestable from Phase 1.

Core Mechanics

The figures below are the canonical values used throughout this guide. Where a later section references one of these numbers, this section is the reference.

Buildings on the map: 16 total — 12 Fortresses and 4 Strongholds.
Season length: Reported as 8 weeks, one phase per week.
Season points per held building: 1 point per Fortress, 2 points per Stronghold.
Continuous control required to occupy: More than 30 minutes within the battle window.
Maximum battle duration: 2 hours per building.
Sign-up time slots: R5/R4 selects 3 preferred time slots; the available pool is reported as 5 slots.

Phase Lifecycle

A Fortress Battles phase has two stages: a Sign-Up stage during the early-to-mid week and a Battle stage that resolves the phase's contests. Phase timing is commonly reported as Monday-through-Thursday sign-ups and Friday battles, but the in-event timer is the authoritative reference for any given server.

Between phases, a Defense Phase covers occupied buildings: a Protection Shield is active and the building cannot be attacked. The Defense Phase ends when the next sign-up window opens, at which point holdings become contestable again.

Season Arc

The structure of a season follows a recognisable pattern that shapes which decisions matter when.

Phase 1 of any season is the only phase with no auto-registrations carried over from the prior week. Every alliance starts with a clean slate, every building is open to whoever signs up, and there are no defensive obligations from prior holdings (since end-of-season holdings do not carry forward). This makes Phase 1 the most contested phase of the season and the easiest phase in which to seize early holdings.

Phases 2 through 7 progressively accumulate auto-registered defenses. An alliance that holds three buildings going into Phase 4 is automatically registered to defend all three; their available manual sign-up slots remain at one Fortress and one Stronghold. Defensive load compounds across the season for successful alliances, while less-successful alliances retain their full manual flexibility.

Phase 8 (the final phase) is unique in that holdings will not carry forward to the next season. The strategic value of late-season expansion is therefore lower than early expansion — a Phase 8 conquest yields the phase's reward bundle and a season-end point, but no defensive carryover. Alliances optimizing season points may still push hard in Phase 8 for the per-building point value; alliances optimizing for resource efficiency may pull back.

For first-season servers specifically, the first three to four weeks involve only Fortresses, and Strongholds entering around week four reshapes target priorities — they introduce a new target class with different reward composition and a higher per-unit point value. Alliances that have established Fortress dominance in early phases are well-positioned to begin contesting Strongholds when they appear.

Registration

R5 and R4 alliance officers handle sign-up. They confirm the Fortress or Stronghold the alliance intends to attack and select 3 different battle time slots from the available pool. Each alliance can sign up for up to one Fortress and one Stronghold per phase.

If it is an alliance's first time participating in Fortress Battles, the alliance is limited to registering for either one Fortress or one Stronghold — not both. For new alliances, this is a meaningful first decision: a Fortress is generally easier (lighter NPC defenders) and yields one season point, while a Stronghold is harder and yields two. On servers where Strongholds are not yet contestable, the choice does not arise.

The final battle time for any given building is determined by the votes of all alliances in the State that have signed up for that building. The time slot with the highest total vote count is finalized as the battle time. Tiebreaker behaviour when vote counts are equal is not explicitly documented.

The voting mechanic creates strategic levers. Each registered alliance contributes its 3 chosen slots to the vote count, and the most-voted slot wins. Alliances registered for the same building can implicitly coordinate by overlapping their 3-slot picks on convenient windows; they can also disadvantage an opponent by concentrating votes on slots that the opponent would find difficult. Defending alliances should pick slots aligned with their core player base's active hours, because a defender's 3 votes can shift the outcome when attacker votes are spread across more options.

Auto-applied registrations (covered below) are reported to be unchangeable once issued.

Auto-Registration

If an alliance occupies a Fortress or Stronghold during a phase, it is automatically registered to defend that building in the next phase of the same season. Auto-registered defenses do not consume the alliance's manual registration slots — the alliance can still sign up for an additional Fortress and Stronghold within the per-phase limits.

The carryover does not cross season boundaries. An alliance holding a building at the end of a season's final phase is not auto-registered for that building in the first phase of the next season; fresh registration is required.

The combination of mandatory auto-defense and per-phase manual expansion is the core engine of season-long position growth. An alliance that successfully defends and expands can theoretically reach the reported maximum of 8 Fortresses and 4 Strongholds across an 8-week season. The constraint is that defending multiple positions simultaneously demands distributed attention, and an alliance that cannot defend an existing holding loses it — the auto-registration then follows the new occupier into the next phase.

The Battle Stage

NPC opening

At the start of each battle, NPC defenders — Phaethon Mercenaries — are garrisoned at the Fortress or Stronghold. The NPCs must be defeated before the building changes hands. Strongholds are reported to garrison significantly tougher NPC defenders than Fortresses, though specific power values are not documented.

Reward eligibility for clearing the opening NPCs is a known point of inconsistency. One stated rule is that only the first player to defeat the Phaethon Mercenaries is eligible for participation rewards, and that rally members who do not personally defeat enemies receive no points for those defeats. A separate, widely circulated account holds that all rally participants share in participation rewards, which is the basis for the common practice of rallying the opening NPCs rather than soloing them. These two accounts conflict; the underlying mechanic is not unambiguously documented, and alliances should expect either behaviour until the actual mail outcome on their server confirms which applies.

Occupation rules

To fully occupy a building, an alliance must be in continuous control of it for more than 30 minutes during the 2-hour battle window. If no alliance achieves the required 30 minutes of continuous control within the 2-hour window, the alliance in control of the building when the window closes is recorded as the occupier. If no alliance contests an occupied building after sign-ups close, the occupying alliance retains control without entering an active battle phase — the timer resolves in their favor automatically.

The 30-minute-of-2-hour structure produces a specific tactical envelope. An alliance that achieves control mid-battle has, in principle, up to 90 minutes of slack before entering the final-30-minute commitment window. A defender that loses control briefly has time to retake it — but the timer's behaviour on displacement is not documented, so partial accumulated time should not be assumed to preserve. The fallback rule (end-of-window holder wins if no alliance achieves 30 minutes continuous) creates a viable alternative path: rather than racing to the 30-minute line, an alliance can play purely for control of the final minutes of the 2-hour window. This is especially relevant when multiple competing alliances trade control across the window and no one can string together 30 unbroken minutes.

Garrison buffs

Squads garrisoned at a Fortress or Stronghold receive Alliance Territory battle buffs only when the building is located inside the alliance's own Territory. A building outside the alliance's Territory does not extend Territory buffs to its garrison, regardless of which alliance currently holds it.

This condition has direct implications for target selection. Buildings inside an alliance's Territory are far more defensible than those outside it, so the realistic defensive footprint of an alliance is bounded by the geographic shape of its Territory. Conversely, when contesting a building outside any alliance's Territory, neither attacker nor defender (assuming the defender is also outside their own Territory) benefits from Territory buffs — the engagement is fought on raw power.

Per-Phase Building Limits

Each alliance can register for at most one Fortress and one Stronghold per phase via manual sign-up. Auto-registered defenses sit on top of this limit rather than counting against it. An alliance that already holds three Fortresses going into a phase is auto-registered to defend all three and can still attempt to seize one new Fortress and one Stronghold — for a maximum of five buildings in play that phase.

The cumulative season-end maximum a single alliance can hold is reported as 8 Fortresses and 4 Strongholds. This figure is a mathematical consequence of weekly auto-registration plus per-phase sign-up limits over the course of an 8-week season, rather than a separately enforced cap. Reaching it would require winning every contested phase from Phase 1 onward without losing a held building at any point.

Leaving an alliance during a battle phase is permitted, but the leaving member cannot participate in Fortress Battles with a different alliance during the same phase.

Rewards

Reward distribution spans several categories that activate at different points in a phase.

Participation rewards are issued based on involvement in the opening NPC clear, subject to the eligibility ambiguity described above.

Victory rewards (also referred to as allocatable rewards) are issued to the first alliance to occupy a building. Victory rewards include allocatable items that R5/R4 distributes to members, with a per-individual cap that prevents the entire pool from going to a single player. An alliance that does not achieve first occupation typically does not receive Victory rewards for that building.

Control rewards are issued to the alliance currently holding a building at scheduled checkpoints during the Defense Phase.

Season Point rewards are issued at the end of the season based on the alliance's accumulated season points. Each held Fortress contributes 1 point and each held Stronghold contributes 2 points to the running total. The total at season's end determines the reward tier — including cosmetic Steam-Mania avatar frames with durations reported across the 3-day, 7-day, 15-day, 30-day, and 60-day brackets.

Reward contents

Common reward items across categories include Gems, Gold Keys, Platinum Keys, Construction / Research / Training / Healing Speedups (across multiple time denominations), General Speedups, Hero XP, and resource boxes for Meat, Wood, Coal, and Iron. Stronghold reward pools in later seasons are reported to include Fire Crystals; Stronghold rewards in earlier seasons are reported as less valuable and not to include Fire Crystals.

The exact item quantities in each reward bundle are not stable across the game: contents rotate from phase to phase, differ between Fortresses and Strongholds, and have changed across seasons. Treat any specific quantities encountered in third-party reward tables as indicative rather than canonical, and verify against the actual mail received on your own server.

Hero shards

Several reward bundles include Hero Shards that rotate based on server hero generation. The reported pattern is that Fortress Battles awards shards for Heroes from two generations behind the server's current generation — for example, a Generation 3 server receives Generation 1 hero shards, and a Generation 4 server receives Generation 2 shards. Which heroes appear in the rotation depends on the active generation.

A note on the "better rewards" framing

Stated rules describe Fortresses as granting better rewards, while the per-building season point values (1 for Fortresses, 2 for Strongholds) point to Strongholds as the higher per-unit yield, and a great deal of strategic discussion treats Strongholds as the more valuable target. These framings appear to conflict, and the conflict is not currently resolved in available documentation. In practice, an alliance's relative valuation depends on whether it is optimizing for per-phase reward bundles (where the stated framing favours Fortresses) or for season-end point accumulation (where Strongholds dominate per unit). Strongholds are commonly treated as priority targets given their higher point yield and scarcer count (4 vs. 12), but the per-phase rewards consideration should not be dismissed.

Decision Points Across a Season

Several recurring decisions shape how a season unfolds for an alliance. Each is grounded in the mechanics above.

Target selection at sign-up. With per-phase sign-up capped at one Fortress and one Stronghold, every phase forces an explicit choice of which buildings to contest. Considerations include location relative to the alliance's Territory (for defensibility if won), expected enemy contestation, the rotating reward composition that phase, and proximity to existing held buildings (for rally and reinforcement logistics).

Time slot selection. R5/R4 picks 3 of the reported 5 available slots. The most-voted slot wins, so the choice is partly tactical: pick slots that fit the alliance's active hours, but also consider what attacker or defender alliances are likely to vote. Concentrated voting carries more weight than spread voting.

Defending versus expanding. Auto-registered defenses cannot be abandoned by changing the registration, so an alliance that holds many buildings is committing to defending them all. The decision each phase is whether to also push into new manual sign-ups, and if so where. An over-extended alliance may lose holdings faster than it gains them.

Season-stage adjustment. Aggression curves should track season stage. Phase 1 favours aggressive expansion (no defenses to maintain). Mid-season favours consolidation (defense load is real, holdings are valuable). Phase 8 favours pure point optimization, since holdings will not carry forward.

Stronghold timing on first-season servers. The arrival of Strongholds around the fourth week reshapes target priorities. Alliances should be prepared to pivot from Fortress dominance to Stronghold contestation when Strongholds activate, because the per-unit point yield is doubled.

Frequently Encountered Questions

Can our alliance change its auto-registered defense target? No. Auto-applied registrations are reported as unchangeable. If an alliance does not want to defend an auto-registered building, the only options are to defend poorly (and likely lose it) or to also dedicate manual sign-up to other targets that phase.

If we hold a building going into Phase 1 of a new season, do we have to fight to keep it? Yes. End-of-season holdings do not carry into the new season's Phase 1. Every Phase 1 sign-up is a fresh registration for every alliance.

Does our auto-defense slot consume our manual sign-up slot? No. An auto-registered defense is on top of the per-phase manual cap of one Fortress and one Stronghold.

Can we sign up for two Fortresses in one phase if we're not signing up for any Stronghold? No. The per-phase manual limit is one Fortress and one Stronghold — the slots are not interchangeable.

What happens if no other alliance signs up to challenge our held building? The occupying alliance retains control automatically when the countdown ends. No active battle phase occurs.

Is the 30-minute occupation timer cumulative or continuous? Continuous. The required threshold is more than 30 minutes of unbroken control. If displaced, partial time should be assumed not to preserve, since timer behaviour on displacement is not explicitly documented.

What if no alliance holds a building for 30 continuous minutes within the battle window? The alliance in control at the moment the 2-hour window closes becomes the occupier.

Can a member who leaves the alliance during a battle phase rejoin a different alliance and continue fighting? No. A member who leaves during a battle phase cannot participate in Fortress Battles with a different alliance during the same phase.

Things to Verify on Your Server

Several aspects of Fortress Battles vary by server progression, by season, or are not unambiguously documented. The items below are the ones most worth confirming against your own server's event timer and reward mail rather than assuming from external reference material:

Specific unlock day for Fortresses and Strongholds on your server.
Whether Strongholds are active in your current season (first-season servers may not see them until around week four).
The exact item quantities in each reward category for each building — these rotate phase-to-phase and differ by season.
The current generation of Hero Shards in the reward rotation.
Whether participation rewards on your server flow only to the first NPC-killer or to all rally participants, since the documented and observed behaviours conflict.
Tiebreaker behaviour when battle time slot votes are tied — the highest-vote rule is documented, but tie resolution is not.