In case you hit the 'Join' button for an Armada but were not able to participate in the attack, this could be why:

Armada Space and Time Requirements
  • Always make sure to join an Armada within the countdown window.
  • Always make sure your ship is within the Armada's Hostile radius at least 10 seconds before the attack begins.
  • Notice that armadas have a limited quota of ships that can participate in the attack. The system will choose the strongest ships by default, so if the amount of ships that joined the armada exceed the armada quota, one or more of those ships will not take part in the action.

    Kindly note that the Armada Leader has the ability to choose which players can participate in the armada.
Not observing any of those rules would make you ineligible for the Armada attack.

The Armada may have been cancelled in the following cases:
  • The Armada Leader left the Alliance before the attack occurred.
  • The Armada Leader had no ships in the Hostile's radius at the time of the attack.
  • The Armada's Hostile Target has been destroyed before the attack occurred.