On 10 May the dying King Narai named his daughter Yothathep as regent. He then learnt that Phetracha was preparing a coup d'état against him. This spurred Phetracha to execute the long-planned coup immediately, initiating the 1688 Siamese revolution. On 17-18 May 1688, King Narai was arrested, and on 5 June Phaulkon was executed. Six French officers were captured in Lopburi and mobbed, one of them dying as a result. Many members of Narai's family were assassinated , and King Narai died in detention on 10 July. Phra Phetracha was crowned king on 1 August. Kosa Pan, the 1686 ambassador to France, became the Minister of Foreign Affairs and Trade. Large-scale attacks were launched on the two French fortresses in Siam, and on 24 June, the French under du Bruant had to abandon their garrison at Mergui. du Bruant and the Chevalier de Beauregard escaped under fire by seizing a Siamese warship, the Mergui. du Bruant and his troops were stranded on a deserted island for four months before being captured by a British warship. They ultimately returned to Pondicherry by way of Madras.
Question: How many fortresses were attacked?
Answer: 2