A half dozen Irish soldiers toting guns with brilliantly polished bayonets formed a guard of honor outside the U.S. Embassy in Dublin as the U.S. flag was lowered to half-staff in one of several solemn ceremonies planned Friday to mark 50 years since the assassination of President John F. Kennedy in Dallas. Similar events were planned for Boston, Washington, and in Dallas. That city will mark the day with a solemn ceremony in Dealey Plaza, through which the president's motorcade passed when shots rang out on Nov. 22, 1963.