Complex sentence: To further dramatize his "royal crusade for independence," Sihanouk, declaring that he would not return until the French gave assurances that full independence would be granted, left Phnom Penh in June to go into self-imposed exile in Thailand.
Split into simpler sentences: To further dramatize his "royal crusade for independence," Sihanouk, declaring that he would not return until the French gave assurances that full independence would be granted. He then left Phnom Penh in June to go into self-imposed exile in Thailand.