The narrations claiming that Imam Hasan (AS) or Imam Husain (AS) fought in wars under the leadership of others are not authentic at all. We don't have any narrations in our books in this regards. Some Sunni authors like Ibn Khaldoon claimed that but with out any authentic evidence or reliable source. Ibn Khuldoon himself lived in the eighth Hijra century and never witnessed nor heard from any authentic narrators.
All the life of Ahlul Bayt (AS) was great Jihad to protect Islam and Islam remained intact just because of the Jihad of Ahlul Bayt (AS).