Complex sentence: On 5 April Norway and Sweden was notified by the United Kingdom of Brittish intentions to place mines on Norwegian territorial waters, and on the morning of 8 April, Brittish destroyers started to lay mines close to Norway.
Split into simpler sentences: On 5 April Norway and Sweden was notified by the United Kingdom of British intentions to place mines in Norwegian territorial waters. On the morning of 8 April, Brittish destroyers began laying mines close to Norway.