The U.S. ambassador to Turkey, John Bass, will represent President Barack Obama in the Gallipoli commemorations to mark the 100th year of the battles that will start on Thursday.Washington's decision has just been delivered to Bass.The U.S. administration had recently decided to send Secretary of Treasury Jack Lew to represent President Obama in Armenia's 1915 incidents commemoration which would be held on April 24.Twenty one heads of state, three vice presidents, two parliament speakers and five prime ministers will attend the ceremonies that will take place between April 23 and 25, along with thousands of other distinguished guests.