Prime Minister Malcolm Turnbull has thanked the Australian and American servicemen who fought in the pivotal World War Two Battle of the Coral Sea on behalf of the generations who followed.
"Our freedoms were secured by the bravery of the fighting men on those ships and the pilots who flew through everything the enemy and the weather could throw in their way," he told a dawn service in Townsville to commemorate the 75th anniversary of the battle.
Families from sailors who served on the aircraft carrier, the USS Lexington that was lost in the battle, have flown from America to attend the service.
Governor General Peter Cosgrove and Queensland Premier Annastacia Palaszczuk are among the dignitaries attending.
Mr Turnbull said the US Navy's commitment to the battle showed "a total commitment to the defence of Australia" and a unity of purpose that continues today.
"Together, we're taking a strong message to North Korea that we will not tolerate reckless, dangerous threats, to the peace and stability of our region," he said.
"And we are united in our efforts to defeat the terrorists in the Middle East and Afghanistan.
"We must be forever grateful to those who put their lives on the line and those who do so today so that we might have a free and peaceful world."
The Battle of the Coral Sea was fought southwest of the Solomon Islands and east of New Guinea from May 4 to 8, 1942.
It was the first decisive halt to the Japanese push south towards Australia during WWII.
It was also the first aircraft-carrier battle and stopped a planned Japanese sea invasion of Port Moresby.
The prime minister will later this week attend a commemorative dinner in New York, where he will have his first face-to-face meeting with US president Donald Trump.
