Complex sentence: On the night of 26 September, they rowed into the harbour and placed limpet mines on several Japanese ships, the limpet mines sank or seriously damaged four Japanese ships, amounting to over 39,000 tons.
Split into simpler sentences: On the night of 26 September, they rowed into the harbour and placed limpet mines on several Japanese ships. The limpet mines sank or seriously damaged four Japanese ships, amounting to over 39,000 tons.