Detained with his mother and other members of the family at a house in Dhanmondi during the war of Liberation in 1971, Jamal found the means to escape and cross over to a liberated zone, where he joined the struggle to free the country. While a student of Dhaka College, Jamal traveled to Yugoslavia for military training under the auspices of the Yugoslav army. Subsequently, he trained at the Royal Military Academy Sandhurst in Great Britain. He joined the Bangladesh Army as a second lieutenant in the East Bengal Regiment.