In Rise of Nations, attack Strength is an attribute of most units, as well as some buildings. In theory, it specifies the amount of damage each attack animation inflicts upon the target. Although in practice, this damage value depends on the damage modifiers or penalties the attacking unit or building has towards its target, which multiply or divide the total damage dealt, respectively. The target's amount of armor also reduces the total amount of damage each attack deals. Due to this, units with a quicker attack rate, but less attack strength, such as the Samurai, might inflict less damage overall than a unit with slower, but stronger attacks, such as the Elite Pikemen that they replace; making the Samurai's perceived advantage only relative to the situation at hand, depending on the target's vulnerabilities and armor rating.
Generally, a unit must take at least 1 point of damage per attack, regardless of the its armor or lack thereof. However, there are exceptions, such as attackers without anti-air capabilities, like Infantry or Lookouts, trying to damage aircraft, or units engaging a target with a significant technological advantage, such as Riflemen shooting at a Battleship.