The sarissa or sarisa was a long spear or pike about 5 to 7 meters in length. It was introduced by Philip II of Macedon and was used in his Macedonian phalanxes as a replacement for the earlier dory,
The Alexander Mosaic, a surviving ancient artistic depiction that probably depicts massed sarissas.
3rd century BCE art of a warrior carrying a spear from the Tomb of Judgement, Lefkadia—possibly a sarissa
The phalanx was a rectangular mass military formation, usually composed entirely of heavy infantry armed with spears, pikes, sarissas, or similar polearms tightly packed together. The term is used tod
Sarissa
…of any spear, even if other Greeks meant specifically the Macedonian variety. The standard Hellenistic army deployment was to have a heavy infantry phalanx in the center, cavalry on the sides capable of threatening to flank the enemy or to attack weak spots, and light infantry skirmishers such as slingers…
Sumerian phalanx-like formation c. 2400 BC, from detail of the victory stele of King Eannatum of Lagash over Umma, called the Stele of the Vultures
A modern illustration of the Greek hoplites marching in a phalanx formation
Phalanx in a frieze on the tomb of Pericles, Dynast of Lycia (380–360 BC)
Greek phalanx against Achaemenid troops