The second war between Makedonia and Rome (201-196 BC), which culminated in the battle of Kynoskephalai ("Dog-Heads") was one of the most important struggles of the ancient world. It broke the Makedonian supremacy in Greece and opened a way for Romans expansion into the East.
This war was in part a second act to a war that started in 215 BC, at which time the Makedonian king Philip V and his Greek allies had signed a treaty with Hannibal and the Carthaginians. Philip, after hearing of the great defeats the Romans suffered at Lake Trasimene and Cannae, hoped he would be able to push the Romans from the so called "Roman Protectorate" in southern Illyria. His objectives were to capture Epidamnos, Apollonia, Kerkyra, Pharos, Dimale and the lands of the Atintanes and Parthioi. But Philip underestimated the Romans - in his first campagin (214 BC) he was soundly defeated by the combined forces of Apollonians and Romans when he attempted to capture the city. The campaign reached new lows when he had to burn part of his recently built fleet (120 lemboi). The fleet had been blockaded inland on the river Aoos by a Roman fleet at the mouth of the river.
The next year Philip attacked again, with greater success. He captured Dasseretis and three fortresses including his objective Dimale. He also persuaded the Parthioi and Atintanes to join with him. Later, probably at the beginning of 212 BC, he took Lissos (with the great fortress of Akrolissos) and all of the Skodra region. These advances reduced Roman possesions to Epidamnos/Dyrrachion, Apollonia and Orikon. With the control over a good port (in Lissos) Philip started to build a new fleet.
At this point there was a great opportunity to coordinate the war effort with Hannibal, but for unknown reasons the Carthaginian fleet under the command of Bomilkar never contacted Philip, refused to draw off the main Roman fleet, and even balked at engaging the small Roman squadron of 25 ships that was protecting Roman holdings in Illyria. Another Roman naval squadron sailed towards Aitolia in the early autumn of 211 BC and with this support the Aitolians signed an alliance with Rome and started raiding territories of states allied to Makedonia. During this stage the Romans captured and massacred Aigina and Antikyra in Phokis. It was recorded that the Romans massacred not only the men, but the entire human population, cut dogs in half, and chopped up and scattered other animals. Meanwhile the Aitolians succeeded in gaining support from Sparte, Elis, Messenia and, more importantly, Attalos of Pergamon.
In 208 Philip, by then allied with Prusias of Bithynia, defeated the forces of Attalos, compelling Attalos to withdraw his entire force operating in Greece. He again tried to contact a Carthaginian fleet that reached Greek waters, but it again retreated without contact. War at land concentrated in Aitolia, where Philip was able to besiege Thermon, the political center of the Aitolian League. In 206, with no sign of a Roman fleet or Roman reinforcements, the Aitolians were forced to accept peace. Following this, in 205, the Romans and Makedonia signed the peace of Phoinike (in Epeiros). The lands that once constituted "The Roman Protectorate" were divided - Philip kept Lissos, Skodra and Atintania while the Romans regained Parthinis, Dimale and two other border cities.

Philip learned in the war that without a strong navy his many successes on land were almost completely wasted. To achieve naval superiority Philip needed bases and money, so he started operations in the Aegean region. He allied himself to the Kretan League and was voted its hegemon. In the winter 203/202, he signed a secret treaty with Antiochos III to divide Ptolemaic territories. Together with Prusias of Bithynia Philip captured or or brought into symmachia the cites at the Bosphoros, including Lysimacheia and Tazos. In the spring of 201 he started an offensive in the Aegean sea, securing the Kyklades, Samos (where he captured some Egyptian ships) and some cities on the Asian coast. Despite this, when he engaged in a naval battle it ended in a draw. Philip had 53 large (pentereis or larger) 150 light (lemboi and the so-called "swordfish") and a few middle-sized ships. Against him the joint fleet of Pergamon, Rhodos and Byzantion numbered 65 large ships, 9 tetreres and 2 triereis. Both sides took great losses (3000 Macedonian soldiers and 6000 crewmen are said to have perished). Following this battle Philip started land operations, raiding Pergamene territory and capturing several Rhodian holdings on the Asian coast. Despite many small successes he was unable to take the heavily fortified city of Pergamon and in the winter of 200 BC his fleet was blockaded in Karia by the rebuilt fleets of Pergamon and Rhodos.
Tensions in Greece were rising at the same time, as Athenai had recently started a war with Akarnania. Philip sent support to Akarnania, a close ally, in the spring of 200 BC, but only after he escaped the blockade. This led Athenai to sign an alliance with Attalos and Rhodos.
Meanwhile, the Romans were watching the unfolding developments with interest, and sent emissaries to and entertained embassies from several parties. There is even the possibility that from 202 BC the Roman commander in the "Protectorate", Marcus Aurelius Cotta, started raiding the Makedonian western border with forces gathered among the Illyrians. At the beginning of 200 BC the Senate tried to start a war but the Comitia turned down the war declaration proposition. Shortly thereafter, emissaries from Athenai and Cotta arrived, reporting that the Makedonian king was recruiting troops and performing intense war preparations on the mainland and islands. They suggested Philip wanted to invade Italy either by sea or from the North, through Illyria. This finally changed the opinions of the Comitia and Senate leaders successfully passed a war declaration. An emissary was dispatched to Philip demanding that he retreat from all Greek cites, restore the Ptolemaic possessions he had captured, and pay reparations for the damages done to Pergamon and Rhodos. The king tried to point out that the peace treaty between Makedonia and Rome had not been violated and asked the Romans not to initiate a war. The emissaries ignored him, and departed, headed to the East, where they sought to disarm any Seleukid or Ptolemaic support for Philip. Before Philip could respond diplomatically, consul Publius Sulpicius Galba landed forces in Illyria, quickly captured Makedonian Antipatreia and slaughtered its population.

In 199 BC the consul tried a few times to break through the Makedonian defences, but Philip refused to fight pitched battles, preferring to harass foraging parties and scouts instead. Three times Sulpicius tried, and three times he was forced to withdraw his half-starved army back to the "Protectorate". After the third failed campaign, the tired Roman soldiers mutinied.
In 198 BC a new consul, Titus Quintius Flaminus, took over command of the Roman forces. Philip fortified the defile of "Aoi Stena" in the Aoos valley (defending not only Makedonia but also his allies the Epeirotai) and repelled some Roman attacks. However, the Romans eventually found a way to bypass Philip's position. In danger of being outflanked, Philip was forced to withdraw, and took up new defensive positions in northern Thessalia. His retreat left the Epeirotai open to attack, forcing them to declare neutrality. At about the same time, the Achaian League broke its alliance and joined the Romans, followed soon after by Athamania.
In 197 BC Philip planned to defend the line of fortresses in Demetrias, Phtiotic Thebes, Echinos and Larissa Kremaste. The main line of defense ran along the Kardang range. Two roads led through it - one from Phthiotic Thebai near Pherai towards Larissa and the second from Pharsalos via Paleopharsalos to Larissa. To hamper Roman foraging Philip evacuated the population and destroyed five cities in the fertile Echinos valley.
At the start of the 197 BC campaign season, Philip gathered his levy at Dion and started training them. It is recorded that he had to call up the full levy, from boys 15 years old to veterans above 55. This was likely because he kept so many forces in so many different places, maintaining substantial garrisons in Thrace, in Karia, in the Aegean Islands, and in Thessaly, aside from his own field army.
Meanwhile, Flaminus had wintered in Phokis and like Philip started his campaign towards the end of March. First he entered Boiotia and forced the League to switch its allegiance from Makedonia to Rome. Next, he returned to Phokis, gathered all his forces, and marched north along the coast, through Thermopylai to Herakleia. At Herakleia he met with Aitolian leaders to discuss the Aitolian contribution to the campaign. After three days he reached Xyniai, and was soon joined there by the Aitolians. Resuming his march he reached the southern borders of Phthiotis in Boiotia, where he was joined by Athamanians and Kretans. Then he tried to take Thebai by treason. Failing in that endeavor, he encamped nearby.
At this point, in late April, Philip had been alerted and had marched his field army south, encamping about 5km north of Pherai. Knowing nothing of each other Flaminus arrived some 9km south of Pherai. The veil of ignorance soon lifted, when on the next day cavalry and light armed troops from each side clashed. Philip found himself, largely by accident, completely outmaneuvered. He was cut off from his main supply bases at Demetrias and Thebai, and the terrain between his army and the Romans was not suitable for battle, as it was covered with walls and small farms. Nor was the Roman position particularly good, and for the same reasons. If Philip could have supplied his army, he likely could have held back the Roman advance and forced the Romans to call of the campaign for that year. But lacking supplies, he pulled out and headed west towards Skotussa, reaching it in the same day his army broke camp. When Flaminus realized the Makedonian force was moving, he also marched west, taking the route along the opposite side of the Kardang range.
On the second day the Romans encamped around a sanctuary called the Theideion. There are at least three propositions for its location, but the Zoodokhos Pege (Lifegiving Spring), which Hammond tentatively identified as the Theideion, seems most likely. Philip camped near Melambion (identified as Khalkhiadhes). The Kardang ridge divided the opposed armies. In the particular place where the armies were camped, the peculiar shape of the hills had led them to be termed the Kynoskephalai, the Dog's Heads. The Makedonian forces comprised 16,000 phalangitai in two wings, 2,000 elite peltastai, 2,000 Thraikians, 2,000 Illyrian Thralles, 1,500 misthophoroi of various nationalities, and 2,000 cavalry. Roman numbers are not precise, but we may assume roughly 22,000 legionary and Italic infantry, 6,000 symmachoi from Aitolia, 1,200 from the Athamanians, and 800 Kretai. The Roman cavalry likely consisted of approximately 2,000 cavalrymen from the legions and alae, and 500 from the Aitolian contingent.
As the armies awoke the following morning a thick fog blanketed the ground. Philip tried at first to pursue his plans and move forward, but the fog was too dense, and he was forced to encamp. Then he sent a force to the summits of the Dog's Heads and sent other parts of the army to collect fodder and forage. Flaminus also sent a force (300 cavalry and 1,000 light armed troops) to occupy the summits of the Dog's Heads. In the mist both forces clashed and the Makedonian forces took the upper hand, pushing the Roman troops back down the hills. After hearing this Flaminus dispatched 500 horse and 2,000 infantry (which may have been a sizable portion of the Aitolian contingent) to reinforce the defeated troops, and this combined force pushed the Makedonians back toward the summits of the hills. At about this point Philip, receiving news of the clash, sent Thessalian cavalry, one Makedonian Hipparchia, and all his misthophoroi--aside from the Thraikians--to lend support in the fight at the summit. This force tipped the balance of the combat back in the favor of the Makedonians. They slowly drove the Romans back down the hills, though the prowess of the Aitolian cavalry impeded the Makedonian advance.
As these larger forces were engaging on the summits, both commanders began preparing their main forces. Philip, encouraged by an overoptimistic report from his advance force, decided to commit to a pitched battle. At the same time, he was worried that the ordering of the phalanx was taking too long, since his forces still had to ascend and descend the ridge to reach the battle. Meanwhile Flaminus, who could see the battle approaching his own lines, was first to ready his troops. He sent forward part of his heavy infantry, which began pushing back the Makedonian cavalry and misthophoroi. By that time Philip had finished preparing the right wing of his phalanx, but the left wing was still approaching in marching columns after forming up. Concerned by the delay, Philip departed for the battlefield with his peltastai and the right wing of his phalanx, having ordered the left wing to follow up as quickly as possible. When he reached the summit, it was evident that his advance force, which had at one point been near the Roman camp, was in retreat before the greater part of the Roman army. Concerned that the advantageous position near the very walls of the Roman camp would soon come to naught, and worried that if he kept his position he might witness the destruction of his light troops, Philip decided to commit his phalanx to the battle. He doubled the depth of his right wing phalangites and peltastai, from 16 ranks to 32, and charged the approaching Roman legions.