Monday, January 23, 2017

A Review and Summary of Impetus

I am admittedly a novice when it comes to Ancient and Medieval wargaming. An obsessive Napoleonic gamer for many years, I have only recently (about a year) crept into this black hole of the gaming world. Starting off with the Hail Caesar rules and being happy with them as an introductory set, I have tried a couple of other rules here and there. Impetus is the latest rules system that I have gravitated to.......and I have found myself playing it almost exclusively now.

Impetus originated in Italy and is published by Dadi and Piombo.   I started, as most gamers have done, by downloading the free rules Basic Impetus and trying them out before jumping into the more complex and comprehensive Impetus rules.  It wasn't long before I purchased the full rules and the Extra Impetus issues filled with army lists (all pdf downloads). Although Basic Impetus is a nice game for quick and dirty battles with a minimum of figures, Impetus contains rules for command and control, discipline tests, and army lists for much larger armies. As a plug, Basic Impetus 2 was just released and is highly recommended for anyone interested in the rules. As for this review, it will be focused on the full Impetus rules.

An Extra Impetus publication featuring a myriad of army lists for specific periods


Each unit represents hundreds of men. Specifically heavy infantry is made up of 600-1200 troops, light Infantry and most cavalry units are made up of 400-800 men, while skirmishers / light cavalry units symbolize 200-300 men. Basing for all figure scales are included in the rules. Since I have units at 15mm scale, each unit has a frontage of 8 cm and adjustable depth based on the type of unit.  As an example, an Anglo-Saxon unit of fyrd (heavy infantry) consists of 12 figures on 2 bases equaling 8cm of frontage and 2.5 cm of depth.

A typical unit of infantry

Units have point values and Impetus armies typically consist of 100, 300, or 500 points (for competition purposes -- I am primarily a scenario gamer).

Ground scale is based on a standard distance called "U," which equals 6-7 meters in real-life distance. For example, "U" for 25mm equals 2 cm on the table, while "U" equals 1 cm for 15mm scale figures.

Each turn simulates approximately 15-20 minutes of time.

Unit ratings

A unit is classified by type (for example heavy infantry, missile troops, light cavalry) and contains several statistics:  movement allowance, VBU (Basic Unit Value) which is a composite rating of typical unit strength and combat/fire capability, and an Impetus rating (dice added to the VBU when charging). Discipline Rating and Demoralization Value (VD -- units that have routed compare their VD to the army total VD to determine victory or defeat) are also present.

For example, the heavy infantry unit above may have the following statistics:

Move = 5U, VBU= 4, Impetus=4, Discipline=C, VD=3, Point value=12, Impetuous

In another example, the Light cavalry unit above has the following statistics:

Move=12U, VBU=3, Impetus=1, Discipline=B, VD=3, Point value=21, Short bow B

Turn Sequence

1. The first step is to decide Initiative, which is very different than most rules. An Impetus army consists of 1-4 commands consisting of multiple units each. To decide Initiative, each player designates one of their commands, adds any leadership bonus, and rolls 2d6. The command with the higher score moves.

2. The command with the initiative activates one unit at a time, either rallying off disorder, placed on opportunity (unit can react to the enemy), moved, fired, or charged into melee.

3. After all units complete their actions, the opposing commanders designate 2 more commands and roll for initiative again.

4. When all commands have been activated (on both sides), the turn is over and the next turn begins.

Command and Control

One of the biggest differences between Basic Impetus and Impetus, command and control is one of the primary aspects of the full rules system. Each army list contains a Command Structure (CS) rating of good, average, or poor. This command structure has a specific range in "U," which is the range that dictates a commander's bonus for rallying from disorder or a negative modifier (if outside this range) for discipline tests.

Each commander has a rating from Charismatic to Cowardly that also dictates how many rallying attempts can be conducted as well as the dice bonus for Initiative rolls.

Moving and Discipline Tests

Moving units, as opposed to rules like Hail Caesar, is pretty restricted. An oblique move or movement to the rear will result in disorder unless the troops are considered light. Multiple moves require a passed discipline test or disorder results. Broken or Difficult ground severely restricts movement as well.

The bottom line is that lighter infantry or cavalry are more flexible in movement, while more disciplined troops and a higher command structure are easier to move around the battlefield. This sounds pretty realistic to me. There is an additional rating for typically barbarian troops, called "Impetuous." Impetuous troops must advance within 30U of the enemy.....imagine hundreds of hairy Germans just itching to charge into those implacable Roman legionaries.

Disorder must be avoided as much as possible. Disorder affects movement, firing, combat-- pretty much everything in the game.

Although "free and easy" movement in other rules systems are fun and quicker to play, I have to say that the restrictive movement in Impetus adds flavor and a strategic subtlety to the game, but is not so complex that it is overwhelming.  As an admirer of realism in miniatures rules, I prefer this approach.

Impetus is especially popular as a tournament game


Placing a unit on opportunity allows the unit to react to the enemy in future phases. The unit on opportunity may fire, opportunity charge, or countercharge. Units within 5"U" of an enemy unit may also react without being placed on opportunity. This is a great way for the non-activated side to remain engaged and turn the game away from a strictly IGO-UGO system.

I need to spend a bit more time with the opportunity rules -- I find that this is one of the more complex concepts within the system.


Firing also makes up a major part of the system. Typically, lighter troops or skirmishers conduct firing (with the exception of a few heavy infantry units, most notably the Roman pila). Firing can cause disorder or actual casualties.

Firing is range and weapon dependent. Bonus dice are added to the VBU and rolled for hits. As in combat, 6's and double 5's result in hits. The number of hits are then rolled against the critical number (VBU rating plus or minus other modifiers) to determine actual casualties.

Firing can be damaging but is typically not as decisive as combat.

Charging and Combat

Units that charge receive a charge distance bonus (1d6 for cavalry, 1d6/2 for infantry). Only units with an Impetus rating of at least 1 may charge (most skirmishers for example have a rating of 0 and therefore cannot charge).

Charged units may attempt to countercharge or, if skirmishers or light cavalry, may evade. Charging units add their VBU and their Impetus rating to determine the number of combat dice to throw. Again, like firing, 6's and double 5's equal hits, and actual casualties are determined in the same way of rolling hits against the modified VBU.

A defeated unit must retreat (rolled dice) a certain distance. If the defeated unit's VBU reaches 0, then it is considered routed and removed from the battlefield.

Period-flavor rules

To add to the realism of the system, there are several special rules for specific armies. For example, the Roman practice of throwing pila either before charging or receiving a charge is covered. Another example is the Shieldwall rule for the Dark Ages. A unit forming a shield wall is restricted in its movement, but if receiving a charge cancels out the Impetus rating dice of the enemy.

Other rules like forming large units, scythed chariots, long spears, and pikes are contained in the rules. This adds considerable period flavor to the system.

Final thoughts

After only about a half-dozen games, I have found Impetus to be a very smooth playing game, but one loaded with subtlety and tactical challenge. After searching through various forum entries and other reviews, the prevailing wisdom is that it takes about 50 games to fully appreciate the "elegance" of the system. I don't know about that, but I can tell you that the more I play it, the more I'm hooked on it.

As for the jewels of the system, I think the command and control and discipline rules are the strengths of Impetus. VBU and the Impetus ratings truly demonstrate differences between different types of troops in an easy to understand format.

I have seen criticism of the system's portrayal of missile fire, which on the surface seems extremely detailed, versus that of combat, which seems simplified. I typically don't have an issue with this, as there is a great variety of missile weapons and artillery that were very range-dependent. When it comes to close combat, a sword kills as easily as a spear. I'm ok with this.

The addition of special rules (detailed above) provide the necessary historic flavor to a period that spans such a great period of years.

Although Hail Caesar, for example, looks great on the table, Impetus requires a smaller number of figures to field an army. It is therefore less expensive to field full armies for any game.

So, in summary, I feel that Impetus is a challenging, yet not overly complex, game that should satisfy any serious gamer. It firmly resides in the spectrum between DBA and rules like Hail Caesar. I'm hooked.....and I'm looking forward to posting more AAR's for Impetus games in the future.