My question is regarding the role of Imam Hussain AS in the reign of Imam Hasan AS and in his battle with muawiya. I have read several books but there was no mention of Imam Hussain or Hazrat Abbas AS in the battle and peace treaty between Imam Hasan and muawiya. Please shed some light on it and i would be grateful if u could mention any books regarding this topic

Historically Imam Hussain was a great support for his brother and stood by him in every step of the way during the difficulties etc

Many books refer to this. For eg the detailed biography of Imam Hasan in Arabic by Sh Baqir Qarashi