The Battle of Trebbia - 218BC

This battle is well known and has been much documented over the years, particularly for rules systems such as DBA. With the growing popularity of WAB we decided to create a scenario that could be played at our local club. It pits the forces of Hannibal against the Roman Legions under Tiberius Sempronius Longus.

Introduction

In late autumn 218BC Hannibal crossed the Alps and entered Italy determined to defeat any Roman opposition that stood before him. It is estimated that he crossed with around 50,000 men and entered Italy relatively unhindered, avoiding major contact with any Roman forces or Gallic tribes as he marched from Spain. Indeed Hannibal recruited several Gallic tribes into his army as he marched on Italy.

The Roman's under the command of Publius Cornelius Scipio tried to intercept Hannibal before he reached the Alps but having failed Scipio headed back to Italy by sea and with his two legions and some allied Gallic tribes under his command secured a strong defensive position on the Ticino River. It was here that he waited for reinforcements as a further two legions had been dispatched by Rome under the command of Tiberius Sempronius Longus.

After recruiting amongst the Gauls in Northern Italy Hannibal began an advance towards Scipio's position. The Romans sent out cavalry and light infantry to 'probe' the forces of the enemy. In one of these skirmishes Scipio himself was injured possibly during an ambush. The Carthaginians continued their advance on the Roman position.

From Bad to worse 

Scipio elected to leave his strong position on the Ticino and retreat in the direction of Placentia.

Roman morale was low and as a direct result several tribes jumped ship and went over to Hannibal. Their decision to defect to the Carthaginians was perhaps linked to the fact that whilst on route Hannibal had recruited a number of Gauls into his service.

With their erstwhile allies defecting the situation was going from bad to worse for the Romans. Scipio therefore chose to retreat to the Trebbia River where he was joined by the two Legions under the command of Sempronius.

December 218 BC was very cold and snowy, Scipio was still recovering from his wounds and it was the turn of Sempronius to command the Romans. The consul was spoiling for a fight with the Carthaginians and the scene was now set for the battle of Trebbia.

The Battle of Trebbia

Hannibal's plan was to draw out the Romans and force them to attack. He also prepared an ambush for the Romans using a small number of light troops. Hannibal's younger brother Mago commanded this force.

Hannibal's sent out Numidian light cavalry to harass the Roman camp. His plan was to goad the Roman consul Sempronius into executing an ill conceived attack. The over eager Sempronius reacted as Hannibal had hoped and after quickly mustering his men in the early morning and dispatching some cavalry to chase off the Numidians he marched the Roman army across the freezing river.

So with the Romans advancing Hannibal began to deploy for battle. He elected to remain some distance from the river and deployed around 8,000 light troops to his front. Behind this he deployed his main battle line comprising of around 20,000 men. The Spanish and the Gaul's in the middle flanked by his African veterans. Around 10,000 cavalry and 37 elephants were split between the two flanks. Mago's ambush force was positioned in a riverbed behind the Roman left rear and was made up of around 1,000 light cavalry and 1,000 light infantry.

Sempronius arranged his 4 legions in the standard Roman formation and was supported with around 4,000 cavalry split across both flanks. Around 3,000 Gaul's were positioned to the right of the heavy infantry and Velites were pushed forward to provide a skirmish screen.

The Battle of Trebbia displayed Hannibal's tactical genius to the full. The highlights of the battle included:

Hannibal's light infantry screen clashed with the Roman skirmishers first. The Velites performed poorly and withdrew.

During the Roman advance the Carthaginian horse, elephant and light infantry engaged the Roman cavalry on both flanks of the Roman position. This Roman cavalry broke and ran from the field pursued by the Carthaginian and Numidian cavalry.

By the time the main battle lines clashed the Roman flanks were under severe pressure from the Carthaginian elephants and light troops. Hannibal's elephants routed the Romans Gallic allies but were eventually driven off by the Roman Velites.

The Roman centre failed to break the Carthaginian line - despite Hannibal's Gallic war bands beginning to buckle. The opposing heavy infantry remained locked in a deadly, bloody hand-to-hand struggle.

At the crux of the battle Mago's ambush was sprung and as he attacked the Romans from the rear the circle around them was complete.

With morale low and fatigue setting in the Romans broke and ran back across the river. Many drowned or were cut down as they fled. Sempronius and around 10,000 infantry managed to retreat to Placentia by fighting their way through the Gaul's. After nightfall Scipio rallied what he could find of the Romans and made off for Placentia and Cremona. It is estimated that around 15,000 to 20,000 of the Roman force died.

Scenario Special Rules 

Fatigue:

One of the main problems for the Romans was fatigue. They had not eaten their morning meal and had forded an icy river prior to the combat.

To simulate this all Roman units must check, before the movement phase, for fatigue from turn 3 onwards. Each unit must roll a D6; if a 1 or 2 is rolled mark the unit as fatigued.

A unit suffering from fatigue will suffer a -1 penalty when calculating any combat resolution. Note that a unit can only become fatigued once but it will remain fatigued until the end of the game

Mago's Ambush:

The Carthaginian ambush cannot be deployed until a non-skirmish Roman infantry unit has engaged a non-skirmish Carthaginian infantry unit. At the start of each subsequent turn, before the movement phase, the ambush is sprung on a roll of 4+ on a D6

The ambush force will deploy anywhere behind the Roman army 12 + 1D6 inches from the nearest unit. If there is not enough room the ambush force will deploy at the table edge.

Orders of Battle

The order of battle is an attempt to reflect the actual units present at Trebbia whilst providing an interesting WAB game. Both forces are around 2,500 points. The choice of units has hopefully allowed us to maintain a degree of historical accuracy whilst providing a playable game that can be completed in an evening.

WAB, like many other rules, allows the selection of balanced armies with which to fight a battle on the tabletop. We have played the game several times and it is possible for both the Romans and Carthaginians to win.

The large number of units in each army means that we recommend the game be played on at least an 8' by 4' table. This will ensure that each unit can deploy as per the scenario map and will still have enough room to manoeuvre. If a 6' by 4' table is used either reduce the number of units on each side or alter the deployment of each main battle line to ensure that it fits on the table.

Warhammer Ancient Battles Special Rules:

Army General

A unit within 12" of the Army General can use his leadership value when taking any leadership test.

The Army General must take any leadership test before any other unit in the army.

Elephant

Elephants cause Fear in enemy infantry and Terror in enemy cavalry units and are immune to psychology (see page 51/52 of the Warhammer Ancient Battles rulebook for full psychology rules) Elephants cannot march move and any movement is halved if not directly ahead.

In melee combat no rank bonuses are counted for either side and all attacks use the elephants WS.

All hits on the elephant are randomised between the crew and elephant. Roll a D6 for each hit 1-4 is the elephant, 5-6 is the crew (the mahout is always the last person hit).

Any leadership tests use the leadership value4 of the Mahout unless he is dead in which case use the elephants.

If an elephant loses a round of melee it automatically stampedes. If it receives one or more wounds from missile fire and it fails a leadership test it will stampede (see page 62 of the Warhammer Ancient battles rulebook for full elephant rules).

Thrusting Spear

Two ranks of infantry fight in melee during the first round of combat provided they were stationary during the movement phase.

Throwing Spear

Two ranks of infantry fight in melee during the first round of combat. Skirmishing infantry and all cavalry may re-roll any to hit dice that missed in the first turn of combat.

Heavy Throwing Spear

Two ranks of infantry fight in melee and gain +1S during the first round of combat. Skirmishing infantry and all cavalry may re-roll any to hit dice that missed in the first turn of combat.