Worst military defeats in Roman history

[Maciamo]

Here is the summary of the worst military debacles suffered by the Romans during over 1000 years of history from the beginning of the Republic to the end of the Western Roman Empire.

In chronological order:

Battle of Heraclea (280 BCE)

Type of battle : pitched battle

Belligerents	Roman Republic	Epirus & Magna Graecia
Strength	45,000 (8 legions + cavalry)	35,500
Losses	7,500 to 15,000 killed + 1800 captured	7,000 to 11,000

Battle of the Trebia (218 BCE)

Type of battle : pitched battle

Belligerents	Roman Republic	Carthage
Strength	40,000 (4 or 5 legions + auxiliaries)	40,000
Losses	26,000 to 32,000	4000 to 5000

Battle of Lake Trasimene (217 BCE)

Type of battle : ambush

Belligerents	Roman Republic	Carthage
Strength	30,000	55,000
Losses	15,000 killed + 15,000 captured	1,500 to 2,500

Battle of Cannae (216 BCE)

Type of battle : pitched battle

Belligerents	Roman Republic	Carthage
Strength	86,400 (8 legions + cavalry)	50,000
Losses	67,500 to 85,500	5,700

Battle of Noreia (113 BCE)

Type of battle : pitched battle

Belligerents	Roman Republic	Cimbri & Teutones
Strength	30,000	300,000
Losses	24,000	light

Battle of Burdigalia (107 BCE)

Type of battle : pitched battle

Belligerents	Roman Republic	Cimbri, Teutones, Volcae + others
Strength	40,000	unknown but very large
Losses	10,000	light

Battle of Arausio (105 BCE)

Type of battle : pitched battle

Belligerents	Roman Republic	Cimbri & Teutones
Strength	120,000 (10–12 legions)	200,000
Losses	120,000	15,000
Remarks	Defeat caused by personal bickering between the two consuls, Quintus Servilius Caepio and Gnaeus Mallius Maximus

Battle of Carrhae (53 BCE)

Type of battle : pitched battle

Belligerents	Roman Republic	Parthian Empire
Strength	36,000–43,000 (7 legions + cavalry)	10,000 cavalry
Losses	20,000 killed + 10,000 captured	38 cataphracts
Remarks	Marcus Licinius Crassus killed

Battle of the Teutoburg Forest (9 CE)

Type of battle : ambush

Belligerents	Roman Empire	Germanic tribes
Strength	16,500 to 22,500 (3 legions)	~ 15,000
Losses	16,000 to 20,000	minimal
Remarks	3 legions destroyed

Battle of Edessa (260 CE)

Type of battle : pitched battle

Belligerents	Rome + Germanic allies	Sassasian Persians
Strength	70,000	unknown
Losses	over 60,000	minimal
Remarks	Emperor Valerian captured

Battle of Adrianople (378 CE)

Type of battle : pitched battle

Belligerents	Eastern Roman Empire	Goths & Alans
Strength	15,000 to 30,000 (7 legions)	12,000 to 20,000
Losses	10,000 to 20,000	unknown
Remarks	Emperor Valens killed

Worst defeats by number of casualties

1. Battle of Arausio (105 BCE) : 120,000 dead
2. Battle of Cannae (216 BCE) : up to 85,500 dead
3. Battle of Edesa (260 CE) : over 60,000 dead
4. Battle of the Trebia (218 BCE) : up to 32,000 dead
5. Battle of Noreia (113 BCE) : 24,000 dead
6. Battle of Carrhae (53 BCE) : 20,000 dead + 10,000 captured
7. Battle of Lake Trasimene (217 BCE) : 15,000 dead + 15,000 captured
8. Battle of the Teutoburg Forest (9 CE) : 16,000 to 20,000 dead
9. Battle of Heraclea (280 BCE) : up to 15,000 dead + 1,800 captured
10. Battle of Adrianople (378 CE) : 10,000 to 20,000 dead
11. Battle of Burdigalia (107 BCE) : 10,000 dead

Note that, except for Adrianopole, none of these battles took place during the declining phase of the empire from the late 2nd century to the fall of the Western Roman Empire in 476 CE. The reason is that battles during the Late Empire were typically smaller in size. There were plenty of small battles against barbarian incursions or local rebellions, but also numerous clashes between emperors and usurpers (Emperor Gallienus had to fight at least 12 usurpers). The few major battles were usually won by Rome (such as the Battle of the Catalaunian Plains in 451 CE).

[Hawk]

Romans totally evolved themselves from the fight against a superior person mentally as Hannibal. Hannibal totally owned them, and i think world history would have better pages if Hannibal sacked Rome. But, their stubbornness and luck won them, as well the jealousy of Carthaginian aristocracy against Hannibal's potential.

Just as the Numidian general said to him: You, Hannibal, know how to gain a victory; you do not know how to use it.

[Salento]

No one knows for sure what kind of “pages” could've been written if history would have been different.

[bigsnake49]

No one knows for sure what kind of “pages” could've been written if history would have been different.

I thought like most other empires, the Romans did not know when to stop expanding.They should have stopped at defensible borders. Italy + Balkans would have been defensible. You add the Gaul, Iberia, part of Germany and Asia Minor and it's no longer defensible.

[Maciamo]

I thought like most other empires, the Romans did not know when to stop expanding.They should have stopped at defensible borders. Italy + Balkans would have been defensible. You add the Gaul, Iberia, part of Germany and Asia Minor and it's no longer defensible.

The Roman empire grew somewhat "organically" without a plan to to conquer the world. It is mainly through the three Punic Wars that Rome asserted its domination over the western Mediterranean. That was because Romans and Carthaginians were mortal enemies. After that regions started to fall under the protection of the Roman Republic on their own. Greek cities asked the help of the Romans to regain their independence from the Macedonians and thus became allies and vassals of the Romans. Lacking an heir, Attalus III of Pergamum chose to bequeath his kingdom to Rome upon his death. Several other regions of Anatolia sought the protection of Rome against the kingdom of Pontus' expansionist policies.

In Gaul, several tribes were allies or client states of the Romans long before Julius Caesar attempted to conquer the region. In fact it was the Aedui, an allied tribe honoured with the title of brothers and kinsmen of the Roman people, that requested Roman assistance to fight the invasion of the Germanic Suebi. Then a few years later the same Suebi pushed into the Alps and caused the Helvetii to migrate in mass toward western Gaul, causing upheaval among Gallic tribes who once again sought Roman assistance to sort their problems. The Sequani started pillaging the lands of the Aedui, Ambarri, and Allobroges, and these tribes, as Roman allies, asked for Caesar's help. Thus started the Gallic Wars, that were in fact Romans and Gauls against other Gauls.

As for Egypt, the kingdom became allied to Rome thanks to Cleopatra's relationship with Caesar then Mark Antony, and was annexed without a fight after Octavian defeated Antony and Cleopatra.

The Balkans were actually one of the regions that had to be conquered with arms through several campaigns, and it really started under Augustus. The Danube frontier was the most difficult to defend throughout Roman history. It could be argued that the empire would have been much easier to defend if the border had run along the Julian Alps and Macedonia, leaving Illyricum/Dalmatia, Pannonia and Moesia to the barbarians like Magna Germania.

Central and Northwestern Iberia were also tough to conquer but remained pacified for centuries afterwards.

[torzio]

The Roman empire grew somewhat "organically" without a plan to to conquer the world. It is mainly through the three Punic Wars that Rome asserted its domination over the western Mediterranean. That was because Romans and Carthaginians were mortal enemies. After that regions started to fall under the protection of the Roman Republic on their own. Greek cities asked the help of the Romans to regain their independence from the Macedonians and thus became allies and vassals of the Romans. Lacking an heir, Attalus III of Pergamum chose to bequeath his kingdom to Rome upon his death. Several other regions of Anatolia sought the protection of Rome against the kingdom of Pontus' expansionist policies.

In Gaul, several tribes were allies or client states of the Romans long before Julius Caesar attempted to conquer the region. In fact it was the Aedui, an allied tribe honoured with the title of brothers and kinsmen of the Roman people, that requested Roman assistance to fight the invasion of the Germanic Suebi. Then a few years later the same Suebi pushed into the Alps and caused the Helvetii to migrate in mass toward western Gaul, causing upheaval among Gallic tribes who once again sought Roman assistance to sort their problems. The Sequani started pillaging the lands of the Aedui, Ambarri, and Allobroges, and these tribes, as Roman allies, asked for Caesar's help. Thus started the Gallic Wars, that were in fact Romans and Gauls against other Gauls.

As for Egypt, the kingdom became allied to Rome thanks to Cleopatra's relationship with Caesar then Mark Antony, and was annexed without a fight after Octavian defeated Antony and Cleopatra.

The Balkans were actually one of the regions that had to be conquered with arms through several campaigns, and it really started under Augustus. The Danube frontier was the most difficult to defend throughout Roman history. It could be argued that the empire would have been much easier to defend if the border had run along the Julian Alps and Macedonia, leaving Illyricum/Dalmatia, Pannonia and Moesia to the barbarians like Magna Germania.

Central and Northwestern Iberia were also tough to conquer but remained pacified for centuries afterwards.

Once Macedonia allied with Hannibal against Rome, Rome had no choice but take Albanian held Macedonian lands from Macedonia to stop any supplies and reinforcements aiding Hannibal, clearly Rome had no choice but to enter the Balkans......then after Hannibal was defeated, Rome turned their attention on Hannibal ally , Macedonia with IIRC a first war at pydna in 168BC ...........the die was cast at this point

Philip of Macedon allies with Carthage

After hearing of Rome's disastrous defeat at the hands of Hannibal at Cannae in 216 BC, Philip sent ambassadors to Hannibal's camp in Italy to negotiate an alliance. There they concluded in the summer of 215 BC a treaty, the text of which is given by Polybius.

The First Macedonian War (214–205 BC) was fought by Rome, The Romans fought the ensuing war ineffectively, and in 205 the Peace of Phoenice ended the conflict on terms favourable to Philip, allowing him to keep his conquests in Dalmatian Illyria ( actually modern Montenegro.)

The Second Macedonian War (200–196)
https://www.britannica.com/place/Cynoscephalae

Third Macedonian War (171–168)
https://en.wikipedia.org/wiki/Battle_of_Pydna

[Maciamo]

Once Macedonia allied with Hannibal against Rome, Rome had no choice but take Albanian held Macedonian lands from Macedonia to stop any supplies and reinforcements aiding Hannibal, clearly Rome had no choice but to enter the Balkans......then after Hannibal was defeated, Rome turned their attention on Hannibal ally , Macedonia with IIRC a first war at pydna in 168BC ...........the die was cast at this point

Philip of Macedon allies with Carthage

After hearing of Rome's disastrous defeat at the hands of Hannibal at Cannae in 216 BC, Philip sent ambassadors to Hannibal's camp in Italy to negotiate an alliance. There they concluded in the summer of 215 BC a treaty, the text of which is given by Polybius.

The First Macedonian War (214–205 BC) was fought by Rome, The Romans fought the ensuing war ineffectively, and in 205 the Peace of Phoenice ended the conflict on terms favourable to Philip, allowing him to keep his conquests in Dalmatian Illyria ( actually modern Montenegro.)

The Second Macedonian War (200–196)
https://www.britannica.com/place/Cynoscephalae

Third Macedonian War (171–168)
https://en.wikipedia.org/wiki/Battle_of_Pydna

I suppose you are referring to what I wrote about Illyricum/Dalmatia being better left outside the empire? But you are referring to the region of Epirus (Albania and northwestern Greece), which was part of ancient Greece, not Illyricum/Dalmatia.

I summarised as quickly as possible the timeline of Roman expansion above, but obviously the war against Macedonia is linked to the Punic Wars too.

[torzio]

I suppose you are referring to what I wrote about Illyricum/Dalmatia being better left outside the empire? But you are referring to the region of Epirus (Albania and northwestern Greece), which was part of ancient Greece, not Illyricum/Dalmatia.

I summarised as quickly as possible the timeline of Roman expansion above, but obviously the war against Macedonia is linked to the Punic Wars too.

I agree with you 100% on your first sentence

I just included why Rome had to go to the Balkans. It was not their intention.

The illyricum/Dalmatia/Pannonia events came to a climax in the 4 year war called the, Great Illyrian revolt, which was much later under the Empire and not the Republic.