Ancient warfare
The memory of the Persian invasion of Greece some 150 years ago was still alive, but the current politics for the Macedonians had put it aside.
Much greater would be the conquests of his son, Alexander the Great, who would add to the phalanx a powerful cavalry, led by his elite Companions, and flexible, innovative formations and tactics. He advanced Greek style of combat, and was able to muster large bodies of men for long periods of time for his campaigns against Persia.

Iron Age Europe: 

Roman Empire: The Roman army was the world's first professional army. It had its origins in the citizen army of the Republic, which was staffed by citizens serving mandatory duty for Rome. The reforms of Marius around 100 BC turned the army into a professional structure, still largely filled by citizens, but citizens who served continuously for 20 years before being discharged.
The Romans were also noted for making use of auxiliary troops, non-Romans who served with the legions and filled roles that the traditional Roman military could not fill effectively, such as light skirmish troops and heavy cavalry. Later in the Empire, these auxiliary troops, along with foreign mercenaries, became the core of the Roman military. By the late Empire, tribes such as the Visigoths were bribed to serve as mercenaries.
The Roman navy was traditionally considered less important, although it remained vital for the transportation of supplies and troops, also during the great purge of pirates from the Mediterranean sea by Pompey the Great in the 1st century BC. Most of Rome's battles occurred on land, especially when the Empire was at its height and all the land around the Mediterranean was controlled by Rome.
But there were notable exceptions. The First Punic War, a pivotal war between Rome and Carthage in the 3rd century BC, was largely a naval conflict. And the naval Battle of Actium established the Roman empire under Augustus.

Balkans: The Illyrian king Bardyllis turned part of south Illyria into a formidable local power in the 4th century BC. He managed to become king of the Dardanians and include other tribes under his rule. However, their power was weakened by bitter rivalries and jealousy. The army was composed by peltasts with a variety of weapons.

The Thracians fought as peltasts using javelins and crescent or round wicker shields. Missile weapons were favored but close combat weaponry was carried by the Thracians as well. These close combat weapons varied from the dreaded Rhomphaia & Falx
to spears and swords. Thracians shunned armor and greaves and fought as light as possible favoring mobility above all other traits and had excellent horsemen.

The Dacian tribes, located on modern-day Romania and Moldova were part of the greater Thracian family of peoples. They established a highly militarized society and, during the periods when the tribes were united under one king (82–44 BC, 86–106) posed a major threat to the Roman provinces of Lower Danube. Dacia was conquered and transformed into a Roman province in 106 after a long, hard war.

Celtic: Tribal warfare appears to have been a regular feature of Celtic societies. While epic literature depicts this as more of a sport focused on raids and hunting rather than organised territorial conquest, the historical record is more of tribes using warfare to exert political control and harass rivals, for economic advantage, and in some instances to conquer territory.
The Celts were described by classical writers such as Strabo, Livy, Pausanias, and Florus as fighting like "wild beasts", and as hordes. Dionysius said that their "manner of fighting, being in large measure that of wild beasts and frenzied, was an erratic procedure, quite lacking in military science. Thus, at one moment they would raise their swords aloft and smite after the manner of wild boars, throwing the whole weight of their bodies into the blow like hewers of wood or men digging with mattocks, and again they would deliver crosswise blows aimed at no target as if they intended to cut to pieces the entire bodies of their adversaries, protective armour and all". Such descriptions have been challenged by contemporary historians. Caesar himself describes the Gauls as forming phalanxes (likely similar to the medieval shieldwall) and testudos in battle, and using spears as their main weapon, as opposed to swords.

Germanic: Historical records of the Germanic tribes in Germania east of the Rhine and west of the Danube do not begin until quite late in the ancient period, so only the period after 100 BC can be examined. What is clear is that the Germanic idea of warfare was quite different from the pitched battles fought by Rome and Greece. Instead, the Germanic tribes focused on raids.
The purpose of these was generally not to gain territory, but rather to capture resources and secure prestige. These raids were conducted by irregular troops, often formed along family or village lines. Leaders of unusual personal magnetism could gather more soldiers for longer periods, but there was no systematic method of gathering and training men, so the death of a charismatic leader could mean the destruction of an army. Armies also often consisted of more than 50 percent noncombatants, as displaced people would travel with large groups of soldiers, the elderly, women, and children.
Though often defeated by the Romans, the Germanic tribes were remembered in Roman records as fierce combatants, whose main downfall was that they failed to unite successfully into one fighting force, under one command. After the three Roman legions were ambushed and destroyed by an alliance of Germanic tribes headed by Arminius at the Battle of the Teutoburg Forest in 9 AD, the Roman Empire made no further concentrated attempts at conquering Germania beyond the Rhine. Prolonged warfare against the Romans accustomed the Germanic tribes to improved tactics such as the use of reserves, military discipline and centralised command. Germanic tribes would eventually overwhelm and conquer the ancient world, giving rise to modern Europe and medieval warfare. For an analysis of Germanic tactics versus the Roman empire see tactical problems in facing the Gauls and the Germanic tribes

Notable ancient wars: Medo-Babylonian war against Assyrian Empire
Ionian Revolt
The Ionian Revolt was a series of conflicts between the Ionia and the Persian Empire that began 499 BC and lasted until 493 BC. The revolt begins because of Athens's offensive attack to the city of Sardis and massacring the Persian citizens by burning down the city. This revolt had a major role in starting the Greco-Persian wars.
Greco-Persian Wars
The Greco-Persian Wars were a series of conflicts between the Greek City-States and the Persian Empire that began around 500 BC and lasted until 448 BC.
Peloponnesian War
The Peloponnesian War was begun in 431 BC between the Athenian Empire and the Peloponnesian League which included Sparta and Corinth. The war was documented by Thucydides, an Athenian general, in his work The History of The Peloponnesian War. The war lasted 27 years, with a brief truce in the middle.
Wars of Alexander the Great
King Alexander the III of Macedonia throughout his entire reign from 336 to 321 B.C embarked on a campaign of conquest of the Persian Empire. Starting from modern-day Western Turkey Alexander the Great conquered the entirety of Egypt, the Middle East, Iran and parts of India and Central Asia. Never losing a battle Alexander expanded the boundaries of the known world to the Greek World at the time. With an untimely death, his successors fought over the territories they had conquered. However, due to Alexander the Great Greek culture and technology spread into Asia for centuries to come.
Kalinga War (265–264 BC) was a war fought between the Mauryan Empire under Ashoka and the state of Kalinga, a feudal republic located on the coast of the present-day Indian state of Odisha. Ashoka's response to the Kalinga War is recorded in the Edicts of Ashoka. According to some of these (Rock Edict XIII and Minor Rock Edict I), the Kalinga War prompted Ashoka, already a non-engaged Buddhist, to devote the rest of his life to Ahimsa (non-violence) and to Dhamma-Vijaya (victory through Dhamma).
Qin's wars of unification
Qin's wars of unification were a series of military campaigns launched in the late 3rd century BC by the Qin state against the other six major states – Han, Zhao, Yan, Wei, Chu and Qi – within the territories that formed modern China. By the end of the wars in 221 BC, Qin had unified most of the states and occupied some lands south of the Yangtze River. The territories conquered by Qin served as the foundation of the Qin Empire.
Punic Wars
The Punic Wars were a series of three wars fought between Rome and the city of Carthage (a Phoenician descendant). They are known as the "Punic" Wars because Rome's name for Carthaginians was Punici (older Poeni, due to their Phoenician ancestry). They determined that the Romans would control the Mediterranean Sea and led to the eventual rise of the greater Roman Empire across Europe, Asia and Africa.
The First Punic War was primarily a naval war fought between 264 BC and 241 BC.