Wargaming the Battle of Gavilan 5 May 1817

John Fletcher has published a scenario for the Battle of Gavilan (5 May 1817). I’ve got supplementary notes related to wargaming that scenario in various places and this post points to them.

Historical Situation

Setting: Gavilan Hill, Conception, Chile; 5 May 1817

Ordonez attempted to defeat Las Heras’s 1,300 patriots before O’Higgins could join with his Chilean forces (Manly, 2008). After leaving Talcaluano the royalists headed for the rebel redoubt on Gavilan Hill (northwest of Concepcion) in two columns. Colonel Morgado had 600 men and two field pieces on the Penco road whereas Ordonez approached from Chepe with 800 and three guns.

Nine royalist gun-boats opened fire on the insurgents within Conception at 0645 hours (Manly, 2008). Ordonez arrived at the insurgent lines first and immediately assaulted Las Heras’s left flank. Ordonez’s column was decimated storming the rebel lines. Morgado arrived an hour and a half later and launched his own attack but with no more success. When the advance guard of O’Higgins army arrived on the field, two Chilean companies, the royalists abandoned the assault and retreated behind the Talchuano trenches. They royalists lost 118 killed, 80 wounded, four guns, and 200 muskets. Patriot casualties were six dead and 62 injured. O’Higgins arrived by nightfall and assumed command over the siege operations, which were to last seven months (Fletcher, 2005).


The key featues are Gavilan Hill (gentle) where the Patriots defended Conception, Chepe Hill (steep) where Ordonez arrived, the Bio Bio river where Martinez arrived, and various marshes (difficult) and lakes (impassable).

Gavilan Table Without Grid
Gavilan Table Without Grid

Pre-game preparation


Patriot Player (Defending)

Deploys first and takes second turn.


Defend Gavilan Hill, and hence Conception behind, by destroying the Royalist force.

Forces Available

Patriot Order of Battle

  • Commander: Col. Las Heras
  • Subordinate Commander: Lt. Col. Freire
  • Cazadores of Argentine 7th Infantry Regiment
  • Cazadores of Argentine 8th Infantry Regiment
  • Argentine 11th Infantry Regiment
    • Fusiliers
    • Elite Companies / Grenadiers & Cazadores
  • Chilean 1st Infantry Battalion
  • Chilean Compania de San Fernando
  • Argentine Horse Grenadiers, 3rd Squadron
  • Chilean Dragoons
  • 4 x 4lbrs
  • 2 x 32lbr howitzers


Deploys first within the blue box on the map.


Reinforcements arrive at 1000 hours:

  • Fusiliers of Argentine 7th Infantry Regiment

Royalist Player (Attacking)

Deploys second and takes first turn.


Destroy the Patriot force defending Gavilan Hill, opening access to Conception beyond.

Forces Available – Ordonez’s Column

All troops start off table and enter at the designated times and places. The first Royalist column – Ordonez’s Column – arrives near Chepe Hill on the first turn.

Royalist Order of Battle – Ordonez’s Column

  • Col. Ordonez – nominal overall commander
  • Conception Battalion
    • Fusiliers
    • Elite Companies / Grenadiers and Cazadores
  • Chillan Dragoons *
  • 2 x 4lbrs
  • 1 x 3lbr

* The Chillan Dragoons skirmished on foot at Maipo so I give the option here. They are either mounted or dismounted for the entire battle.

Reinforcements – Morgado’s Column

The second Royalist column – Morgado’s Column – arrives at the designated point on map some time after Ordonez’s column arrives.

Royalist Order of Battle – Morgado’s Column

  • Col. Morgado
  • Ad Hoc Infantry Battalion **
  • Frontier Dragoons
  • 2 x 4lbrs

** The Ad Hoc unit was formed from a mixed bag of survivors from Chacabuco that had spent some weeks at sea attempting to flee to Peru.

Reinforcements – Martinez’s Column

The third Royalist column – Martinez’s Column – arrives at 1000 hours from the Bio Bio River:

Royalist Order of Battle – Martinez’s Column

  • Col. Martinez
  • Los Angeles Infantry
  • Indians on foot with assorted weapons
  • 1 x 4lbr

Victory Conditions

The Patriots on Gavilan Hill are trying to stop the Royalist columns from reaching Conception.

Scenario Special Rules

Game start

As per John’s scenario… Patriots deploy first. Battle begins at 0700 hours. Royalists deploy second and have initiative on first turn.

Patriot Redoubt

Although the map has a redoubt on Gavilan Hill John Fletcher notes that it was little more than a sentry post so you should probably ignore it for game purposes.

Wargaming Challenges

The battle is a bit one sided. The Royalists don’t have numerical superiority and to make it worse they arrive in a dispersed manner. When they do arrive they have to advance in the face of alerted defenders armed with cannon. It wasn’t pretty historically and it isn’t going to be pretty as a game.

The balance all depends on two factors:

  1. The potency of the cannon in terms of range and killing power
  2. How fast the Royalists can advance, hence how long they are in killing range

Rules where the Royalist troops move quickly across the table, and don’t take undue casualties in the process from cannon fire, will work better as a “balanced” game.

In the interests of balance you might also increase the Royalist potency. For example:

  • Improve the morale of the Ad Hoc Infantry Battalion. This unit was formed from a mixed bag of survivors from Chacabuco that had spent some weeks at sea attempting to flee to Peru. John Fletcher lowers their morale as a consequence, from 5 to 7 (which is worse). You could just make them normal morale for regulars
  • Increase the size of the Ad Hoc Infantry Battalion. For example, in my Liberators QPR Scenario I increased the number of stands from 3 to 10 to aid game balance.
  • Make all Royalist units a bit stronger relative to their numbers. For example, in Liberators QPR you might give all historical units (not game units) an extra stand
  • Increase the size of the Indians on foot with assorted weapons. Although these are ill-armed and arrive late in the battle are are unlikely to have a big effect.

Scenarios, Games and Battle Reports

So far I’ve refought this battle using two rule systems:


Fletcher, J, (n.d.) The Battle of Gavilan – May 5, 1817. Grenadier Productions. [Available on-line at Liberators 1810-1830 Yahoo Discussion Forum in the Files page.]

Fletcher, J. (2005). Liberators! Volume 1: The War in the South. Grenadier Productions.

Marley, D. (1998). Wars of the Americas: a chronology of armed conflict in the New World, 1492-1997 [2nd ed.].

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