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  • Martin Boulter

Clash of Empires The Battle of Trebbia 218 BC

In this article I’m going to use the Clash Battle System to recreate the Carthaginian general Hannibal’s victory over the Romans at Trebbia in 218 BC. Trebbia is significant because it is the first major battle in which Hannibal demonstrated his military genius and it is the only battle in which his use of war elephants contributed to his victory. In fact, they were also used at Zama at the end of the Second Punic War (202 BC). However, that was a Carthaginian defeat.


Rome’s designs upon Spain which was rich in resources and within the Carthaginian sphere of influence provoked the Second Punic War 218 – 201 BC. The Carthaginian general Hannibal decided to take the fight to Rome itself and marched an army of 20,000 infantry, 6000 cavalry and about 40 elephants across the Pyrenees and the Alps to arrive in northern Italy. Here the Carthaginian army was reinforced to nearly double its original strength by Celts from the Po Valley. They wanted revenge upon Rome for their earlier defeat and subjugation. A Roman army of some 40,000 men under the command of two consuls confronted the invaders on the west bank of the river Trebbia near the modern town of Piacenza. In the frigid conditions of late December, the two armies formed up on an open plain. Hannibal had picked his ground well and concealed an ambush force commanded by his brother Mago in a drainage ditch behind the Roman army. In the centre of his line Hannibal placed his expendable Celtic and Spanish troops while on their flanks he positioned his elite Libyan infantry in phalanx formation and reinforced by war elephants. On the opposing side the Romans adopted their usual array of three lines of heavy infantry in the centre and cavalry on the flanks. As predicted the serried ranks of Roman legionaries used brute force to punch their way through the Carthaginian centre. On the flanks the Libyans and elephants held. Meanwhile, Hannibal had used his superior cavalry force to neutralize the Roman cavalry while the ambush force blocked off any escape route to the rear. Now the Roman flanks disintegrated under the impact of the Libyan infantry and elephants. Thereupon, those Romans that pressed forward through the centre escaped while the rest of the army was slaughtered. The Romans lost about 30,000 troops while the Carthaginian losses were about 5000 men most of these being Celts and Spaniards that could be replaced. At Trebbia the Romans had a taste of what was to come namely the near extinction of Rome at the hands of one of the most brilliant military tacticians of the ancient world. 

Clash of Empires

Using the Clash of Empires rules the battle strength and capabilities of the belligerents can be shown as follows: -

Carthaginian Army

The Carthaginian army consists of 35 units inclusive of cavalry. There is also 1 War Elephant unit but that doesn’t count towards outnumbering an opponent. It is a Mixed army which uses 1D8 and 1D6 (highest scoring die only) for its Battle Dice and has an army ratio of 3:2:1. The primary army type is the Part-Standing African Phalanx, the secondary army type Gallic and Celtiberian Warband and the tertiary army type Citizen Hoplite Phalanx (Italian mercenaries). The Pre-generated Army Ratio Table in the rulebook shows that an army of 32 units in the ratio 3:2:1 will consist of 16 Primary units, 11 Secondary units and 5 Tertiary units. This means that there will be 16 Part-Standing African Phalanx units at Combat Rating , 11 Gallic and Celtiberian Warband units at Combat Rating and 5 Hoplite Phalanx units at Combat Rating . On the Combat Rating to Fighting Bonus Conversion Table in the rulebook this equates to +13 FB for the 16 African units, +3 for the 11 Warband units and +2 for the 5 Italian Hoplite units. In addition to this Carthage gets to roll for 1D6 allied Numidian units. This is a special advantage available to Carthage for an army of 12 or more units. A 3 is rolled so therefore the army now also includes 3 Numidian Mounted Warband units at Combat Rating which converts to +1 FB. This gives a total of +19 for the Fighting Bonus which is added to the Battle Roll. The primary Battle Bonus belongs to the African Phalanx and is 1D8 (x2) which can be activated on an odds or evens score on the Battle Dice. The (x2) is a double bonus which is awarded on an odds or evens score and an Initiative win. The Carthaginians also benefit from the Celtic Warband special advantage Battle Rush (+1D6) and the Numidian special bonus (+1D4) for Deadly Shots. Each bonus can be activated by a verbally declared odds or evens score on 2D6. There is no double bonus with these special advantages. The Carthaginians also have a Heavy Cavalry upgrade which gives them a +1D8 Battle Advantage Die as well as the normal +1 to Initiative for cavalry. As for Hannibal he is ranked as a Great Commander and rolls 2D6 (highest scoring die only) for Initiative. Under Hannibal the Carthaginian army has a superior command structure +2 Initiative and for this battle Hannibal has decided to place 20% of his army’s FB that is +4 in reserve to protect vulnerable points in his battle line. This means that the normal -1 penalty to Initiative for an unwieldy Hoplite Phalanx is negated. Therefore, the Carthaginian army rolls 2D6 +3 for Initiative. Lastly, at this early stage in the campaign Hannibal also has 1 War Elephant unit in his army. This has a Combat Rating of which converts to +1 FB and can reduce an opponent’s Battle Roll by 1D6 for Panic on an Initiative win. However, the opponent does get a saving throw and if successful the War Elephant’s CR is reduced to which in this case will convert to 0 FB and the Panic roll drops to 1D3. In this battle the Carthaginians have a slight advantage in numbers especially cavalry and therefore get a +1D6 bonus for outnumbering their opponent.

Note: - Admittedly, of all the armies in the game, the control of the Carthaginian army with its many different components is the most difficult. However, this would have been the case with the actual army on the day and is testament to the genius of Hannibal that he was able to manage such a multi-faceted force so skilfully.

Republican Roman Army

The Republican Roman army consists of 32 units inclusive of cavalry. It is a Part-Standing army which uses 2D8 (highest scoring die only) for its Battle Dice and there is no army ratio for this army. A Part-Standing Roman Legionary army has a Combat Rating of . On the Combat Rating to Fighting Bonus Conversion Table this equates to +16 FB for 32 Roman Legionary units. The Roman Legion hasn’t got a Battle Bonus, but it does have a Special Ability called Relentless. This allows the Roman army to save against defeat by rolling 5-6 on 1D6. This can be used for a field battle and once only. If successful, the Roman army can fight again. In this refight any tactical or numerical superiority that either side might have is negated, but the Roman army will get a manipular support bonus of +1D6. If the Romans choose not to refight then they can disengage with 25% losses to the loser and 10% losses to the winner. The Romans also have a Light/Medium cavalry upgrade which gives them a +1D6 Battle Advantage Die and associated +1 to Initiative for cavalry. On the day of the battle command of the Roman army falls to the consul Titus Sempronius Longus. He is ranked as competent and rolls 1D6 for Initiative. Therefore, the Republican Roman army rolls 1D6 +1 for Initiative. 

Clash Battle System

After rolling for Initiative the Battle Roll for each army consists of the following procedure: -

Roll Battle Dice (highest scoring die only)

Plus, Combat Rating (CR) to Fighting Bonus (FB) (conversion dependent upon number of units)

Plus, Fighting Technique Battle Bonus (activated by odds or evens Battle Dice)

Plus, Advantage Dice (representing a numerical, tactical or other special advantage)

Highest score wins and the difference between the two Battle Rolls determines the number of casualties.

Battle Log



Battle Dice

No. of Units

CR to Fighting Bonus/Battle Bonus if applicable

Battle Advantage Dice

Total Score

2D6 +3 =

4 and 2

(Highest die only)

4 +3 = 7


1D8/1D6 =

6 and 3

(Highest die only)



x3 Numidian ❶ +1 FB


x1 War Elephant unit ❺❷ +1 /+0 FB = +1

Panic (1D6/1D3) = 1D6 = - 2 to opponents Battle Roll

❸ x 16 = +13 FB

❶ x 11 = +3 FB

❷ x 5 = +2 FB

Numidians = +1 FB

Total = +19 FB – 4 FB (Reserve) = +15 FB

Battle Bonus

+1D8 (x2) = N/A

Battle Rush (1D6) = N/A

Deadly Shots (1D4) = 2

Heavy Cavalry +1D8


Opponent outnumbered +1D6


Tactical Advantage +1D6


5 + 1 + 2 = 8

6 + 1 + 15 +2 + 8 = 32

Note: - The Carthaginians win Initiative by 2 which yields a +1D6 Tactical Advantage. This combined with a slight numerical superiority especially in cavalry contributes to the rout of the inferior Roman cavalry. In this part of the action the Numidian cavalry distinguish themselves with their Deadly Shots from javelin skirmishing. (Odds are called and a 3 and 5 are rolled on 2D6. Thus 1D4 = 2 for Deadly Shots). As a result of this the flanks of the Roman infantry are exposed to attack from the African phalanxes and War Elephants. However, having rolled a 6 and 3 on the Battle Dice the African Phalanx fails to activate its Battle Bonus which required odds or evens dice. Nevertheless, under pressure from these troops and the impact of the War Elephants who cause panic the Roman wings disintegrate. Although the Roman centre manages to break through the Celts, who fail to activate their Battle Rush, the rest of the army is annihilated. The Carthaginians lose 7 units and the War Elephant unit must save against loss on 4-6 on 1D6. A 3 is rolled so the elephant unit is destroyed.

Republican Roman


Battle Dice

No. of Units

CR to Fighting Bonus/Battle Bonus if applicable

Battle Advantage Dice

Total Score

1D6 +1 = 5





2D8 =

4 and 3

(Highest die only)



(8 Legions)

x 32 = +16 FB



Relentless 5-6 1D6 = 3

Light/Medium Cav + 1D6 = 5

4 + 16 + 5 = 25 – 2 = 23  

Note: - Despite losing Initiative the heavy Roman infantry steadfastly press on and manage to break through the Carthaginian centre. The Roman flanks, however, stripped of their cavalry protection are soon assailed by the African Phalanx and War Elephants. The fate of the Roman army is sealed when their rear is attacked by the Carthaginian ambush force and they subsequently fail to make their Relentless Roll. The difference between the two Battle Rolls determines the number of casualties which for the Romans is 75% of their army i.e., 24 units.

The Carthaginians win a decisive victory over the Romans at the Battle of Trebbia 218 BC. Figures by Irregular Miniatures from their 25mm Greek & Roman range. Painted by Silurian and from the author’s own collection. The numerical strength of each army is denoted by blank coloured poker chips. Game board from the Clash of Empires: The Hellenistic World Game.

The Celtic and Spanish warriors break under intolerable pressure from the compact ranks of heavy Roman infantry. However, the Roman flanks are soon assailed by the Carthaginian war elephants and African infantry which results in the bulk of the Roman army being destroyed. Figures by Essex Miniatures from their 15mm Ancients range. Painted by Silurian and from the authors own collection. Army composition calculated by the Clash Conversion Table for Wargaming.


Boulter, M. L. 2009/2024: Clash of Empires: The Hellenistic World. Silurian War Games Ltd.

Dupuy, R. E. and Dupuy, T. N. 1993: The Collins Encyclopaedia of Military History. Harper Collins Publishers.


Goldsworthy, A. 2001: Cannae. Cassell & Co.


Hackett, J. 1989: Warfare in the Ancient World. Sidgwick & Jackson Ltd.


Head, D. 1982: Armies of the Macedonian and Punic Wars 359 BC to 146 BC. A Wargames Research Group Publication.


Mellersh, H.E.L. 1995: Chronology of the Ancient World, 10,000 BC – AD 799. Helicon Publishing Ltd.

Wise, T. and Healy, M.1999: Hannibal’s War with Rome. The Armies and Campaigns 216 BC. Osprey Publishing Ltd.

Article Front Page Picture

Punic War, in which Romans and Carthaginians fought (3rd-2nd Century BC). After Alamy (IY04446764).

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