Complex sentence: In 1950, with Ngô Đình Diệm not making much impact, he and Thục applied for permission to travel to Rome for the Holy Year celebrations at the Vatican but went instead to Japan to lobby Prince Cường Để to enlist support to seize power.
Split into simpler sentences: In 1950, with Ngô Đình Diệm not making much impact, he and Thục applied for permission to travel to Rome for the Holy Year celebrations at the Vatican. However, they went to Japan to lobby Prince Cường Để to enlist support to seize power.