For nearly two and a half years following this initial engagement, Japanese Army and Naval Air Forces maintained a constant surveillance of northern Australia, ranging from Broome on the west coast to Horn Island in north Queensland.

[3] The Japanese air raids against mainland Australia, though very wide-ranging and seemingly unrelated in strategic terms, did in fact have considerable impact on General MacArthur's south-west Pacific strategies, particularly during 1942.

Although Darwin had been attacked by an aerial force numerically equivalent to that which had paralysed the American Pacific fleet at Pearl Harbor, the main thrust of the Allied war effort was then being directed towards the defence of Port Moresby which, until then, had been subjected to just a few, ineffectual nuisance raids.

For almost two years the Japanese Air Force was able to maintain a bomber offensive which significantly disrupted and delayed the Allied war effort, whilst simultaneously causing considerable anxiety within the Australian civil community.

The first of these categories, and the first offensive operations of the northern campaign, were anti-shipping strikes directed primarily against Allied ships trying to resupply the beleaguered ground forces in Timor and Java.

Japanese anti-shipping operations had actually commenced on 8 February 1942 – almost two weeks before the first raid on Darwin – when the minesweeper HMAS Deloraine was attacked by a dive-bomber just 112 kilometres west of Bathurst Island.

Mr M. Takahara (who, after the war, became an executive director of one of Japan's largest stockbroking firms) was the flying boat's observer at the time, and one of only two crewmen to escape the encounter unscathed.

[7]Takahara and the other five crewmen who survived the crash were able to draw some comfort from the knowledge that the Japanese Army Air Force did eventually capitalize on their success in locating the Allied convoy.

Anti-shipping operations were resumed on 18 February when the Army supply ship, MV Don Isidro,[8][Note 3] was attacked by a Japanese plane north of the Wessel Islands in eastern Arnhem Land.

[10] The Catalina pilot, Lieutenant Thomas H. Moorer, survived the attack and subsequently submitted a comprehensive report, which is now considered to be the earliest contemporary account of an aerial combat in northern Australia.

There was no alternative but to land down wind and this procedure was rendered even more hazardous by the fact that the float mechanism had been destroyed by gunfire ... noise caused by bullets striking the plane was terrific ...

[Note 4] These anti-shipping operations did not cause any lasting disruption to the Allied coastal supply route and the Japanese flying boat bases at Taberfane and Dobo in the Aru Islands were constantly attacked throughout 1943 by No.

Reconnaissance flights were conducted throughout the entire campaign and the last Japanese aircraft to fly over Australia during the second world war was a Mitsubishi Ki21 (Sally), piloted by Lieutenant Kiyoshi Iizuka.

Radar plots showed that the Dinahs would cross the coast at extreme altitude and enter a shallow dive during the return flight, gradually gaining speed until they were well clear of the fighter and anti-aircraft defences.

[13]The losses sustained through anti-shipping and reconnaissance operations were comparatively slight, however, when it is considered that nearly one hundred and sixty Japanese aircraft were destroyed over Australia during the mainland bombing offensive.

The RAAF became so heavily committed to patrolling the Australian coastline that by April 1943 it had reached the stage where it had more operational squadrons on duty in Australia than in the northern frontline theatres of New Guinea.

The raids on Townsville and Mossman Archived 16 February 2011 at the Wayback Machine in July 1943 were another exception to this general rule as these were carried out by Emily flying boats from the 14th (Yokosuka) Air Group, operating at extreme range from Rabaul, New Britain.

The pattern of attack changed dramatically on 25 April that year when the 753rd Air Corps, led by Lieutenant Commander Matsumi, arrived over Darwin with a force of twenty-four bombers escorted by fifteen fighters.

As one Department of Civil Aviation official noted at the time:[This quote needs a citation] We waited for the fifth raid of 27 bombers in succession with a sick feeling in the pit of the stomach.

I think it was the worst day in my life I have spent to date, just waiting for something to eventuate, which did not.The Japanese subsequently used this tactic to great advantage, repeatedly sending over small unescorted formations at night.

The Japanese would often arrive at altitudes in excess of 6600 metres (21,654 feet) and the Allies' greatest defence, in these circumstances, was the early warning radar network which could detect incoming formations at distances of up to 240 kilometres (130 nautical miles).

[18] The following extract from his combat report describes the events of that morning: After flying about among the clouds for about half an hour I spotted two series 97 dive bombers with a fixed landing gear on a course heading for Batchelor Field.

was to examine enemy aircraft wreckage and collect any data plates that had escaped the attention of the souvenir hunters, so as to monitor changes in armament, crew capacity, camouflage, airframe and engine design.

Intelligence data turned up in the most unlikely circumstances, as for example in September 1942 when a 'party of 77 squadron personnel while on leave discovered two attache cases, with Jap markings, found to contain electrically heated flying suits and other personal gear'.

Twenty-four Allied aircraft were destroyed in the space of fifteen minutes whereas only one Zero, piloted by Chief Air Sergeant Osamu Kudo, was brought down by anti-aircraft gunners.

By detecting the incoming formation at a range of approximately 130 kilometres the CSIR's experimental radar station at Dripstone Caves, near Darwin, had effectively proved the usefulness of the concept of radar-controlled interception to a largely pessimistic military and civilian community.

The Americans failed to intercept during the next five raids and on 2 April the Shell oil refineries in Harvey Street were struck by bomb splinters, causing 136 000 litres of aviation spirit to be lost.

Successes like these were not always the order of the day: at Exmouth Gulf in Western Australia on 24 September 1943 a flock of birds sitting atop the antenna triggered an air raid alert.

The squadron's arrival coincided with a period of reduced enemy activity and although it remained in the region until early 1943, it later left for Milne Bay without ever meeting the Japanese on equal terms.

These activities made a worthwhile contribution to MacArthur's advance along the north New Guinea coast by destroying installations and forcing the enemy to retain defences well to the rear thereby weakening the front.