Complex sentence: In World War II he commanded the first force sent to Port Moresby and the Kokoda Track after the Battle of the Coral Sea, which was the first force deployed in what is regarded in Australia as Australia's most important military campaign.
Split into simpler sentences: In World War II he commanded the first force sent to Port Moresby and the Kokoda Track after the Battle of the Coral Sea. This was the first force deployed in what is regarded in Australia as Australia's most important military campaign.