Complex sentence: Through letters, Alfassa had remained in contact with her son Andre Morisset ever since leaving for Japan, though he was prevented from visiting by the outbreak of World War II. In 1949 he finally arrived in Pondicherry.
Split into simpler sentences: Through letters, Alfassa had remained in contact with her son Andre Morisset ever since leaving for Japan. He but was prevented from visiting by the outbreak of World War II. In 1949 he finally arrived in Pondicherry.