An archaic unit, the Pikeman has low attack and three main advantages: high siege damage, high speed, and large multipliers against cavalry. While they are not suited to fighting any other units except cavalry, they are effective at supporting other units who are harassing the enemy. This is mainly by threatening their key buildings such as their military production. If they are engaged by infantry at all, their best move is to simply run out of range, thanks to their high speed. For example, Pikemen themselves should not be engaging Settlers/Villagers because Settlers actually have higher melee damage and can actually defeat the Pikemen in a duel. Despite having more speed than most infantry, they are not fast enough to pursue cavalry and are better used defensively to respond against cavalry attacks, rather than chasing them.
Pikemen are usually created in small numbers and rarely created outside of the Commerce Age. This is for multiple reasons: firstly, while the Pikeman is 20% cheaper in raw resources than a Musketeer, it costs wood, which is slower to chop. Secondly, the other anti-cavalry units (Musketeers and Dragoons) are vastly more versatile unit options because they can engage other units than cavalry without requiring overwhelming numbers. Thirdly, army sizes increase to the point that dedicated siege warriors are no longer necessary to threaten buildings. Fourthly, the other units can be further upgraded to stay useful in later ages, whereas archaic units largely cannot be upgraded. In short, other infantry units replace its siege role while also having melee capabilities, while ranged cavalry replaces its ability to quickly fend off cavalry attacks, and while they can't fulfill an identical role to the Pikemen, overall these units are a better replacement.
They can be defeated by most other units, but are particularly countered by ranged infantry and artillery. In the Commerce Age, they are useful for destroying buildings, since most civilizations lack artillery at that stage. Pikemen are useful as a front line defense for ranged units to position behind. Using them with Crossbowman is an effective combo early in the game, as they can take out infantry at long range while the Pikemen defeat any cavalry that get too close.
Spanish players have the option of being able to almost instantly (2.7 seconds) train Crossbowmen and Pikemen in the Commerce Age, due to the "TEAM Archaic Soldier Training" and "Fencing School" Home City Cards. If Standing Army from the Church is used, Pikemen and Crossbowmen can be created instantly.
In the Definitive Edition, The Papal Guardpolitician upgrades the Pikemen into the Guard level for free and allows them to be upgraded to Imperial. This opens some new strategies for the five aforementioned European civilizations. A French player, for example, should consider Pikemen as a faster and cheaper alternative to Halberdiers if they just serve to protect artillery/Skirmishers from melee cavalry or boost anti-building damage of the player's own cavalry. All civilizations in question, except for the Swedes, can do the same with their Crossbowmen, which allows the player to keep using the archaic combo into the late game. Keep in mind that gather rates for wood and infinite coin are equal (when equally upgraded) and Skirmishers have better multipliers agains heavy infantry, so this strategy is best if the player a) already has a big stockpile of food and wood, but lacks coin (most likely to be the case immediately after reaching the Industrial Age), b) really likes investing coin into expensive artillery or c) has access to additional upgrades for either archaic infantry in general or archers in particular, be it through native civilizations or TEAM cards.
Upgrade Pikemen to Imperial (+50% hit points and attack); requires Guard Pikemen and The Papal Guard (French, Germans, and Portuguese)
Upgrade Tercios to Imperial (+50% hit points and attack); requires Tercio
Upgrade Dalkarls to Imperial (+50% hit points and attack); requires Dalkarl
As seen above, the Spanish and Swedes are the only civilizations with access to Pikemen that can upgrade them beyond Veteran.
(Definitive Edition) French, German, and Portuguese Pikemen will be automatically upgraded to Guard if The Papal Guard is chosen to advance into the Industrial Age, which also allows Pikemen to be upgraded to Imperial.
(Definitive Edition) The British can also upgrade Pikemen beyond Veteran (The Papal Guard is not needed).
Spanish Royal Guard/Consulate Pikemen are named after the Tercio infantry organization system used by Spain during the Habsburg era.
Swedish Royal Guard Pikemen's name refers to the Dalecarlians.
The Russians originally had the Pikeman, as there are voice files for Russian Pikeman in the game files and in the Scenario Editor which are used by the Russian Petard.
Pikemen fought in very tight formations that maximized the danger to enemies as they approached. The front rank would set their pikes against a cavalry charge, placing the butt of the staff against the ground, braced by the instep of their back foot, with the tip raised up at an angle. The rank standing just behind the first would hold their pikes straight out at about shoulder height to add still more stabbing spearheads. As firearms developed, they were integrated into units of pikemen. By the mid-seventeenth century an infantry regiment might be composed of two-thirds musketeers and a third pikemen. Eventually firearms with mounted bayonets came to replace pikes, which were little seen or used after the nineteenth century.
A typical pike was a 10- to almost 20-foot spear-like wooden staff with a steel or iron spear point. Some pikemen also carried swords and axes to attack any enemies who survived the deadly bristling of pike formation. They wore helmets, and sometimes breastplates, to defend themselves against attacks.