By Lucia Newman CNN Havana Bureau Chief

                 HAVANA, Cuba (CNN) -- Cuban President Fidel Castro led a march
                 Thursday morning commemorating the start of the Cuban Revolution
                 48 years ago. Cuban officials said as many as 1.2 million people -- about
                 one-tenth of the island's population -- were expected to participate in
                 the observance.

                 Castro was flanked by the two grandsons of Iran's Ayatollah Khomeini
                 and top members of the Cabinet and the communist party, as he joined a
                 throng of marchers waving Cuban flags and other large banners.

                 The observance is traditionally celebrated with a speech by Castro, but no
                 speeches were planned this year.

                 The procession was working its way down the Malecon, the city's famous
                 waterside drive, and past the U.S. diplomatic mission.

                 Buses began arriving in the capital at 1 a.m. Thursday, shuttling thousands
                 of people in for the march.

                 The Cuban Revolution has its roots in the July 26, 1953, attack on the
                 Moncada army barracks in Santiago by Castro's forces. The anniversary
                 is a major event in Cuba's revolutionary calendar.