Dhaka, Dec. 26 -- As dusk settled over the city on Thursday, a red-and-green bus rolled slowly through a sea of chanting supporters and stopped at the gates of Evercare Hospital. At 5:54 p.m., Tarique Rahman stepped inside - not as a triumphant political leader alone, but as a son coming to see his ailing mother.

Inside the hospital lay Khaleda Zia, the former prime minister and chairperson of the Bangladesh Nationalist Party, whose long illness has kept her largely out of public life. Outside, thousands awaited people for a glimpse of the man who had been absent from the country for more than 17 years, their voices rising in slogans of loyalty, hope and defiance.

For Tarique Rahman, the moment carried a weight that went beyond politics...