The battle of the South China Sea started on January 16,1974 when the Republic of Vietnams navy (South Vietnam) spotted the Chinese People’s Liberation Army in the Crescent group of the Western Paracel Islands which was an un-planned “visit” and South Vietnams territory. This event led to a two day close-proximity battle and an on shore firefight Where the Chinese forces overwhelmed the Vietnamese forces. After the on-shore fight the Chinese destroyed or severely damaged all of the Vietnamese naval vessels the Vietnamese forces retreated and now the Crescent group is Chinese territory.
The Vietnamese attacked the Chinese ships because they were in their territory and armed without notifying Vietnam so the South Vietnamese attacked to get the Chinese out of their territory.
China wanted the control of all of the Paracels having already controlled the Amphitrite group attacked and conquered the crescent group so they could then control the whole of the Paracels.
My recomendation for peace would be for China to not have gotten involved and be content for what they already have. Also if the U.S. got involved then there might have been ongoing consequences and higher tensions with China.