It was fought by Allied (United States and Australian) and Japanese aircraft against four different major groups of warships.

Some of the aircraft involved were land-based, but most  were from the opposing aircraft carriers.

It was the first aircraft carrier battle ever fought.

The first naval battle in which the opposing forces of surface ships at no stage sighted or fired at each other. All attacks were carried out by aeroplanes.

It is also the largest naval battle that has ever been fought  off Australia’s shores.

Japanese losses: One small carrier destroyed, one carrier severely damaged, one destroyer and three small naval ships sunk, 77 carrier aircraft lost, and 1074 men killed or wounded.

The Japanese damaged the American fleet and the Americans halted the Japanese invasion of Port Moseby.

This turn of events was way against the initial plans that the two parties had made before the start of the war.

The Battle of Midway also contributed to these effects.

The American Task Force 17, formed around Rear Admiral Fletcher's carrier USS
Yorktown, was already in the Coral Sea. Task Force 11, formed around Rear
Admiral Fitch's carrier USS Lexington, was further away to the north-east. My
ship, together with HMAS Canberra and HMAS Hobart, comprised Rear Admiral Sir
John Crace's Australian cruiser squadron known as Task Force 44. These three
Allied naval task forces were ordered to rendezvous in the Coral Sea between 1
and 5 May 1942 to confront the Japanese seaborne invasion forces moving against
Port Moresby and Tulagi. HMAS Canberra was still undergoing a refit at Sydney
and was unable to participate in the coming battle. On 5 May 1942, all three
Allied task forces had assembled in the Coral Sea. Incidentally, 5 May 1842 was
my nineteenth birthday.

On 6 May
we all fuelled from the US tanker Neosho which was then sent south with her
destroyer escort USS Sims, ostensibly out of harm's way. We now know that while
we were fuelling on 6 May, the Japanese carrier striking force was doing the
same, and only 70 miles north of us.

On 7 May,
our cruiser squadron, together with the American heavy cruiser USS Chicago and
three American destroyers, was detached from the main force and sent to the
Jomard Entrance which separates the islands of the Louisiade Archipelago from
the eastern tip of the New Guinea mainland. We were expecting the Japanese
invasion force to traverse the Jomard Entrance on its way to Port Moresby. Our
job was to block the southern exit to the Jomard Entrance to prevent the
invasion force reaching Port Moresby. The US carriers remained further back,
aiming to strike the enemy fleet carriers with their aircraft when they
approached.

I still claim that I heard the torpedoes in my action station in the bowels of the
Australia.
A few minutes later, twenty-one heavy bombers (thought to be ''Nells"), escorted
by eleven Zeros, attacked Australia from astern and up-sun at a height of about
18,000 feet. Bombing was accurate. Some twenty 500 lb bombs and several smaller
ones were dropped, and we were straddled in all directions, and our upper decks
were drenched with spray. These aircraft had only just gone when three more,
flying even higher at 25,000 feet, dropped bombs close to the destroyer USS
Perkins which was just ahead of us. Admiral Crace later reported that it was
subsequently discovered that these aircraft were US Army B-17 Flying Fortress
heavy bombers operating from Townsville. He also said in his report that they
were good enough to photograph our force a few seconds after bomb release, thus
proving that they had attacked their own ships.