750 BCE - 510 BCE: The semi-legendary celeres or trossuli - a 300-man cavalry corps which the first kings of Rome incorporated into the legion - is formed, later their number is increased to 600.

578 BCE - 535 BCE: Servius Tullius, the king of Rome, increases the number of the cavalry corps (equites) to 1,800.

498 BCE - 493 BCE: Rome defeats the Latins.

400 BCE: The Roman cavalry is expanded to include riders who can pay for their own horse.

396 BCE: Roman expansion begins with the capture of Veii from the Etruscans.

390 BCE: "Gallic Catastrophe:" Brennus of the Senones defeats the Romans at Allia, and subsequently sacks Rome.

343 BCE - 341 BCE: First Samnite War (Rome vs. Samnites).

326 BCE - 304 BCE: Second Samnite War.

298 BCE - 290 BCE: Third Samnite War. Victory for Rome, peace with the Etruscans.

297 BCE: Celts and Samnites join forces and defeat the Romans at Camertium.

295 BCE: In a battle lasting all day, Romans narrowly defeat a force of Celts and Samnites at Sentinum.

285 BCE - 282 BCE: Rome defeats the Celts in Italy. Rome's dominance in central Italy is secured.

284 BCE: Gauls of the Insubres and Boii tribes defeat the Romans at Arretium.

283 BCE: Rome decisively defeats the Senones at Picenum.

280 BCE - 272 BCE: Roman war against Tarentum. Rome conquers Tarentum. Rome's dominance in lower Italy is secured.

264 BCE - 241 BCE: First Punic War. Carthage cedes Sicily to Rome.

250 BCE - 200 CE: Originally a Celtiberian weapon, the Gladius Hispaniensis was commonly used by Roman soldiers for more than four centuries.

229 BCE - 228 BCE: Rome fights Illyrian pirates. Queen Teuta pays tribute to Rome.

222 BCE: Rome conquers Cisalpine Gaul (modern-day Provence, France).

216 BCE: Hannibal wins the battle of Cannae, the worst defeat in Roman history.

214 BCE - 205 BCE: First Macedonian War: Rome defeats Philip V of Macedon.

200 BCE - 196 BCE: Second Macedonian War: Roman victory.

194 BCE: Romans defeat Antiochus III at Battle of Magnesia.

193 BCE: The Boii are defeated by the Romans, suffering, according to Livy, 14,000 dead.

190 BCE: Battle of Magnesia ad Sipylum, disastrous defeat for Antiochos III against Romans.

172 BCE - 168 BCE: Third Macedonian War: Perseus of Macedon challenges Rome and is defeated.

168 BCE: Romans defeat Perseus of Macedon at Pydna.

149 BCE - 146 BCE: Third Punic War.

149 BCE: Rome sends an army of 80,000 infantry and 4,000 cavalry to attack Carthage.

133 BCE: Rome captures Numantia. End of Iberian resistance.

113 BCE: Romans defeated at Noreia by the Cimbri.

107 BCE - 100 BCE: Gaius Marius reforms the Roman army.

100 BCE: Roman cavalry riders are by now classified as auxilia and organised in wings or alae.

88 BCE - 63 BCE: Mithridates of Pontus fights three wars to free Greece from Rome.

86 BCE: The Roman general Sulla sacks Athens and the port of Piraeus.

63 BCE: The Roman general Pompey defeats the Seleucid Antiochus XIII and incorporates Syria as a province of the Roman empire.

58 BCE - 51 BCE: Julius Caesar's conquest of Gaul.

58 BCE: Caesar attacks the Helvetii while on migration and defeats them.

57 BCE: A Roman army under Caesar narrowly defeats an army of Nervii, Atrebates, and Viromandui.

56 BCE: The navies of Rome and the Veneti Gauls clash resulting in a Roman victory. This is the first recorded naval battle in the Atlantic Ocean.

55 BCE - 54 BCE: Julius Caesar's expeditions in Britain.

53 BCE: Battle of Carrhae. Crassus is captured and executed by the Parthians.

52 BCE: Julius Caesar is defeated at Gergovia by Vercingetorix.

52 BCE: After becoming trapped and besieged at Alesia, Vercingetorix surrenders to Caesar.

27 BCE - 19 BCE: Cantabrian Wars: Roman conquest of the Iberian Penninsula.

27 BCE: Augustus creates the Praetorian Guard.

2 BCE: Augustus appoints two Prefects (praefectus praetorio) to command the Praetorian Guard.

5 CE: The term of service for the Praetorian Guard is extended from 12 to 16 years.

6 CE: Augustus creates the aerarium militare, a treasury drawn from taxes in order to fund a professional Roman army.

9 CE: The Rhine River is established as the boundary between the Latin and German speaking worlds, following the defeat of the Roman army, under the command of Varus, at the Battle of the Teutoburg Forest.

15 CE: Germanicus leads 12,000 men across the Rhine to attack the Chatti.

23 CE: The castra praetoria, permanent camp of the Praetorian Guard, is built in Rome by Sejanus.

43 CE: Claudius commences the Roman conquest of Britain.

60 CE - 61 CE: Boudicca's Revolt in Britain.

75 CE - 77 CE: Romans defeat the last of the Northern tribes; Roman conquest of Britain complete.

101 CE - 106 CE: Trajan conquers Dacia.

167 CE - 180 CE: Marcomannic Wars.

192 CE: Emperor Commodus is murdered, civil war ensues (until 197 CE).

195 CE: First Parthian war.

270 CE: The cohortes urbanae in Rome is given its own camp, the castra Urbana.

293 CE: Emperor Carausius assassinated by Allectus.

312 CE: Constantine defeats Maxentius at Milvian Bridge.

324 CE: Constantine I defeats Licinius at Chrysopolis.

367 CE: Picts, Scots, Saxons, and Franks attack the Roman Empire.

455 CE: Vandals sack Rome.

488 CE - 493 CE: Theodoric the Great of the Ostrogoths conquers Italy.

536 CE - 562 CE: The Byzantine Empire conquers Italy.

607 CE - 627 CE: East Rome defeats Sasanian Persia.