The Battle of Pharsalus

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The Battle of Pharsalus

• Historic Battles

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The Battle of Pharsalus
The Battlefield - Northern Greece, near the
town of Pharsalus (August 9th, 48 BC).
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The Battle of Pharsalus was fought on August 9th,
48 BC, between the armies of Gaius Julius Caesar
and Gnaeus Pompeius Magnus (Pompey). The army of
Caesar amounted to about 22000 Legionaires, 1000
Cavalry and a small number of light troops.
They faced the army of Pompey which was a much
larger army consisting of 110 cohorts of
Legionaires and Auxiliaries giving Pompey a
force of 45000 men together with some 3000
archers, 1200 slingers and about 7000
cavalry. The battle itself was fought on the
Plain, which was surrounded on three sides by
hills and on the fourth side by the river.
About the armies - Caesars army consists of
veterans. They were good quality troops and
very loyal to Caesar. This also applies to the
cavalry. The small number of light troops is
considered average. Pompeys army consisted of 6
legions, one veteran, two average and three
poor, some seeing conflict for the first time.
He had 7000 cavalry which were supported and in
turn supported archers and slingers. The
cavalry were considered to be of average
quality. They were certainly no match for
Caesars infantry with their long spears.
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There is a theory which says that the rate at
which the size of one group changes is directly
proportional to the size of the opposing
group. Consider two opposing groups of sizes
n and m where we assume that n is greater
than m. Then and
where c1 and c2 are constants.
On multiplying both sides of the first equation
by 2c2n and both sides of the second equation by
2c1m we obtain
which integrates to give c2n2 c1m2 constant
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This can be rewritten as
where c is a constant.
The ratio will give a measure of the
relative strengths of the two groups for if c1
lt c2 then group n is the superior group in
battle, and if c1gtc2 then group m is the
superior. If c1 c2 then the two groups (or the
sum of the individual units which make up the
groups) could be considered to be of equal
strengths. If at some stage of a battle n N
and m M, say,
then we can calculate the constant c.
We have and so
.
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Using this equation we can find the number of
survivors S in a battle. Letting n S when
m 0 , the number of survivors S is given by S
int ( N2 M2 1/2) where int is the
integer part of the number if we consider whole
survivors only.
You are going to select values for the ratio
and fight the battle of Pharsalus. Use your
own tactics, take control of Caesars army and
win the battle. To help you choose the ratio,
the table shows the number of survivors for
different values of , if 50 of Caesars
infantry went into battle against 40 of
Pompeys infantry.
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Remember that Caesars army consisted mainly of
battle hardened men (good fighters) while a lot
of Pompeys men had little if no experience in
battle. See if you can adopt a strategy to win
this battle. You might be willing after choosing
your value of , to engage in a centre
battle trying to split Pompeys force and taking
them on in two separate battles as shown in the
diagram below.
With your superior quality troops this might be
a good tactic. Can you could win this battle with
0.8?
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What about a different split? What about other
parts of the battlefield? Just how good do the
parts of your army have to be to overcome
Pompeys army and win the battle of Pharsalus?
Try other strategies and other values for, and
see if you can win the battle?
The battle itself - So what happened in the
actual Battle of Pharsalus? Caesars concern was
that his smaller army would be outflanked on his
right by Pompey
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To combat this Caesar had arranged a group of six
cohorts (about 3000 men) to stand behind his
cavalry on the right. These were to become the
troops which would win the battle for Caesar.
Caesar hid these troops behind his cavalry
hoping they would be unseen by Pompey. This was
done to stop Pompey getting behind his troops
and attacking the rear of his army. Pompeys
cavalry and their supporting archers struck at
Caesars right and began to outflank Caesars
exposed flank. At exactly the right moment
Caesar ordered his infantry in and the cavalry
were routed. The archers were left exposed and
fled or were trampled by their own horsemen.
With the centres of both armies locked in battle,
and Pompeys cavalry fleeing on his left, Caesar
reinforced his centre and wheeled his troops on
the right now to attack Pompeys unprotected
left.
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Pompeys army crumbled and retreated to the
fortified camp. Caesar now offered all
remaining Romans in Pompeys army the chance to
stand aside while he slaughtered the allies
which made up the other part of Pompeys army.
In the battle Pompey lost about 23000 men. Caesar
lost about 1200. History tells us that Pompey
fled to Egypt where he was assassinated by
Pharaoh Ptolemy XII. Caesar was left as Supreme
Commander of the Roman Empire and was
assassinated a few years later.