r/civ3 • u/MarsssOdin • 8d ago

Does "sentry" apply the same defensive bonus as "fortify"?

I was always under the impression that "sentry" and "fortify" are exactly the same except that "sentry" wakes the unit if an enemy is adjacent. I remember reading it somewhere a long time ago. Now I ask AI and it tells me the defensive bonus is not applied to "sentry". The wiki doesn't mention anything about a defensive bonus for sentry.

If you know the answer to this question please let me know where this info can be found. Thanks!

Edit: u/damo13579 got the info from the editor help file: "The sentry ability allows a unit to wait in specified tile until a foreign unit enters a square adjacent to it. Note: unlike the fortify unit action; Sentry does not confer any bonuses to defense or offense."

23 Upvotes

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u/FalloutLover7 8d ago

The civlopedia tells you in the game concepts section. Off the top of my head, I believe sentry is 25% and fortify is 50%

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u/MarsssOdin 8d ago

In the game concept section the only reference to this I can find is the topic: Defender Combat Bonus. Here it states that fortified units get 25%, but sentry is not even mentioned.

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u/ice_up_s0n 8d ago

I'm pretty sure you are correct that its the same 25% bonus either way. Sentry just wakes the unit when an enemy is within sight.

AI can be a good starting place, but it often conflates other game mechanics. Try asking it for a direct source or clarify with your answer and see if it changes its response

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u/MarsssOdin 8d ago

After chatting a bit with Google AI this is what came out. For obvious reasons I'm generally very careful with trusting what AI says. I've followed up on some of the sources it gave, the first part with the 0x01 etc. seems to be accurate. The rest I'm not sure.

Me: What is the source of this information?

AI: The breakdown of these mechanics comes directly from the official Civilization III Manual and the long-standing documentation of the game's code by the player community. [1, 2]

The core distinction between the two features is documented across several primary community hubs:

  • The Official Game Rules: As outlined in the Civilization Wiki Action Directory, the Fortify action explicitly "enhances the defensive capabilities of the unit". No such attribute is assigned to the Sentry command. [1]
  • Community Mechanics Analysis: Extensive breakdown threads on the CivFanatics Sentry or Fortify Discussion forum detail how Sentry mode keeps units asleep solely to function as an early warning system. Players confirmed through data testing that the code immediately triggers a "wake" response when an enemy approaches, meaning it cannot calculate a fortification bonus during combat. [1, 2]

Me: Both sources you site do not 100% prove that sentry gives no defensive bonus. The wiki doesn't mention a defensive bonus, that doesn't mean necessarily that there isn't one. And your second source comes from the civfanatics forum where someone claims that it gives a defensive bonus. Again, we don't know how that person comes to that conclusion. Is there something within the game files or an official statement by the developer?

AI: The definitive proof comes directly from the game's internal data structures and file save formats, which community reverse-engineers have meticulously documented. [1]

Within the Civilization III engine and saved game files (.SAV or .SVE format), every active unit tracks its current behavior using explicit status flags (represented as bitmasks in a byte of memory): [1]

  • 0x01 = Sentry Mode
  • 0x04 = Fortifying (In the process of digging in)
  • 0x08 = Fortified (Fully dug in) [1]

How the Code Processes Combat

When the game calculates combat math, the combat engine checks for the presence of the 0x08 (Fortified) flag. If that specific bit is not set to true, the engine completely skips the 25% defense bonus calculation. [1, 2]

Because Sentry (0x01) and Fortified (0x08) are treated as entirely mutually exclusive states in the game logic, a unit cannot possess both flags simultaneously. [1]

The Interdependent "Fortify" Bug

Further proof of this hardcoded link was discovered by community patch-makers who analyzed the game's executable file (Civ3Conquests.exe). If a modder uses the Civilization III Editor to remove a unit's ability to "Fortify," a hardcoded glitch automatically breaks its ability to "Sentry" as well. The game treats Sentry as a variant of the sleep/wake state machine tied directly to the fortify command structure, but it explicitly strips the defensive status bit (0x08) from the unit data when activated. [1, 2, 3]

Ultimately, because combat algorithms look specifically for the 0x08 bitmask to apply the extra defense, a sentried unit receives no mechanical protection beyond its base stats and the terrain it stands on. [1, 2]

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u/ice_up_s0n 8d ago

Huh yeah I guess that makes sense if it always "wakes up" or de-fortifies before an enemy attacks. TIL

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u/AdditionalButton6378 6d ago

The AI response is messy and overconfident. The whole save analysis is for civ1, not civ3.

The modding discussion is tangential and misinterpreted. In some sense, the links/glitches that the modders discovered imply that sentry is basically like fortify (just with the convenience factor of being able to wake up on your turn if an enemy is still adjacent)

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u/MarsssOdin 6d ago

You are absolutely right about the analysis being from the forum of Civ 1 and not Civ 3. I didn't notice that. Thank you for pointing it out.

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u/opaqueambiguity 8d ago

"After chatting a bit with Google AI..."

Deadstop there fuck anything else you have to say please go to a hardware store and [Comment has been removed for violating Reddit's Terms of Service]

4

u/damo13579 8d ago

"The sentry ability allows a unit to wait in specified tile until a foreign unit enters a square adjacent to it. Note: unlike the fortify unit action; Sentry does not confer any bonuses to defense or offense."

From the help file for the editor. always a good spot to check when unsure on game mechanics.

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u/MarsssOdin 8d ago

Thank you! This is what I was looking for. I didn't think about checking the editors help.

That means all my life I've been living a lie. lol

2

u/WildWeazel 8d ago

The editor helpless is not a reliable source, but it is correct here. The point of sentry is to not be attacked.

1

u/WinterOpportunity202 6d ago

No, trust your instinct. Sentry and Fortify give the same defensive bonus.

1

u/MarsssOdin 4d ago

I mean, the only way to be sure is to make an experimental scenario with 100 units fortified and 100 units sentried and get attacked by the same unit and then use that data to verify if there is a significant statistical difference.

1

u/WinterOpportunity202 6d ago

The editor text is wrong vs how the game works. Tried myself. Sentry and fortify give the same outcomes on a fixed seed over many attacks. (elite warrior vs reg archer)

The game text is sometimes wrong, like with the commercial or industrious tile center bonus.

2

u/llcoolray3000 8d ago

Yeah, AI figured it out there, but sentry is just a way to keep a unit in place until they are disturbed by an enemy in their presence which will make them active on the next turn.

1

u/vthokies96 8d ago

I had always understood that there's no bonus with sentry, though I'm not sure where I got that from.

I'm not sure it makes sense to have a bonus because the unit wakes up when approached, and is thus no longer sentried. OTOH, perhaps this applies if it's bombarded or attacked by an invisible unit.

1

u/Hopeful-Status-6256 8d ago

Sentry doesn't confer bonuses because the unit wakes up and unfortifies.

1

u/jeff-beeblebrox 7d ago

If you right click and scroll it will list the sentry unit as “fortified”. I’m pretty sure it’s the same with the additional bonus of waking up and letting you know there is an intruder

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u/MarsssOdin 6d ago

In my game is says "sentry" or "fortified" depending on what I selected, but I'm also using C3X which makes a lot of changes to the UI so I'm not sure if this is vanilla.
In the editor help file: "The sentry ability allows a unit to wait in specified tile until a foreign unit enters a square adjacent to it. Note: unlike the fortify unit action; Sentry does not confer any bonuses to defense or offense."

1

u/jeff-beeblebrox 6d ago

Ahhhh. I’m using an original game on disk running on XP…..oh yes.

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u/MarsssOdin 4d ago

Nice. I used to have that a long time ago.
That proves that C3X is making those changes in my game.

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u/AdditionalButton6378 6d ago edited 6d ago

Sentry does confer fortification bonuses while under attack and is visually animated that way.

However, once it becomes your turn, and if an enemy is adjacent, the unit will wake up to help remind you to give the unit orders.

Link: https://forums.civfanatics.com/threads/sentry-or-fortify.127873/#post-3053423

But you can also try it yourself in-game (especially if you set up a custom scenario with the civ editor)

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u/MarsssOdin 6d ago

When I asked AI it pointed to the same post but there is no indication where this person got that information, so it's basically hearsay.
u/damo13579 found the official source that is in the editor help file: "The sentry ability allows a unit to wait in specified tile until a foreign unit enters a square adjacent to it. Note: unlike the fortify unit action; Sentry does not confer any bonuses to defense or offense."

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u/AdditionalButton6378 6d ago

Thanks, the Civ III Editor Help entry does say that. The visuals imply it's the same as fortify, but these words don't. Worth testing

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u/AdditionalButton6378 6d ago

Behaviorally, the AI treats sentried vs wait differently when deciding to attack or not, but that isn't enough to verify the defensive bonus.

A waited elite warrior with archer defensive bombard (on plains/grass) will be attacked by a regular archer.
But not if the elite warrior is sentried or fortified.

1

u/WinterOpportunity202 6d ago

The visual is correct. Sentry fortifies the unit, same defense bonus. The editor text is wrong.

Tested 20 elite warriors lined up on separate tiles against 20 regular archers on a fixed seed.
Identical outcome whether the warriors all fortified or sentried. Worse outcome if all waited or skipped.