A story of an unexploded bomb from World War II always make national headlines, as was the case recently. But how many more are there out there?
In mid-2024 a small bomb was found at the Darwin waterfront on a construction site. [1] Another was located in 2022 where a shiplift facility was being built. [2] In 2010, a 250kg bomb was found near Tiger Brennan Drive, with another located there in 2015. [3] They are just the latest in a long series of finds since the end of World War II.
It’s hardly surprising. Darwin suffered the biggest air raid of the war on Thursday 19 February 1942. Launched from four Japanese aircraft carriers, 188 enemy aircraft attacked Darwin around 1000. The force was made up of 36 Zero fighters, 71 Val divebombers, and 81 Kate high-level bombers. They dropped 681 bombs – one which didn’t go off is displayed at Darwin Military Museum. Two hundred and thirty-six people were killed; and hundreds more wounded. But that was only the start of the air raids.
As this author researched for The Empire Strikes South, until mid-1944 Japanese aircraft raided northern Australia. There were 1,883 individual aircraft flights, making up 208 sorties, sometimes with more than 60 machines at a time. Sorties ranged from Exmouth in Western Australia to Townsville in Queensland. Bearing that in mind, this analysis covers only the Darwin region, in an attempt to at least get an initial handle on the problem.
The NT saw 135 incursions, with 77 of them able to be classified as raids into the Darwin area. The main composition of a raiding force was bombers escorted by fighters, but sometimes fighters alone made up the attacking force – for example nine Zeroes raided Broome WA on 3 March 1942, killing 86 people in Australia’s second most deadly air raid, and “fighter sweeps” were regular conducted in the NT too.
To calculate exactly how many bombs were dropped on the Northern Territory is difficult. The bombers could carry various configurations of ordnance. But to give at least some idea of what we’re dealing with, all of the flights have been counted which were made by the main bomber utilised, a twin-engined machine called the Betty. (All Allied codenames for Japanese bombers used girls’ names; fighters used boys’) The Betty type made 603 flights into the NT, with most of the raids concentrated around Darwin, although one attack reached 300 kilometres south to Katherine. The Betty’s bombload consisted of one 1,000 kilogram bomb; or two 500 kg weapons, or one 500 kg and 10 x 60 kg bombs. [4]
The first raid from the aircraft carriers dropped 681 bombs; more, as is often claimed than were released over Pearl Harbor, although the tonnage of the Hawaii raid was more.[5] If we do the necessary sums, we find the following possibilities:
- First raid’s 681, plus 603 bombers carrying one 1,000 kg bomb = 603 bombs: total 1,284. However a look at records confirms the single bomb load was not carried in raids over Australia, OR
- First raid’s 681, plus 603 bombers carrying two 500 kg bombs = 1,204 bombs: total 1,885, OR
- First raid’s 681, plus 603 bombers carrying ten 60 kg bombs = 6,030 bombs: total 6,711. The Japanese records show this is the load carried by all Betty’s in NT raids.[6]
Since WWII, there have been many such similar problems around the world, in places which were heavily bombed, for example London, Berlin, Malta, Tokyo, and so on. Some suggestions have been made that 10% of WWII air-dropped bombs did not detonate. [7] Since WWII around 45,000 unexploded devices have been found in Britain.[8] In 2016, it was calculated that more than 2,000 tons of unexploded munitions are uncovered on German soil every year.[9]
Given a 10% estimation, Darwin and surrounds may have 670 unexploded bombs around it, less those found and made safe or detonated. However, there are a number of caveat factors for such a scenario.
It could feasibly be argued Japanese military technology in the early 1940s was superior to that of the Allies, and this leads to a lesser number of bombs failing to go off. The Zero fighter was unarguably the best fighter in the Pacific at that time. Their naval torpedoes were more reliable than the American Navy’s – torpedo firing problems dogged the USN submarine branch for an extended period. Japanese warship hull designs, and their shipboard sighting optics were also superior.[10] Maybe 10% unexploded can be realistically changed to 5%
Given Darwin is surrounded by sea it is likely a lot of bombs fell into the water. The fighter protection for the area steadily improved from the forlorn ten United States Kittyhawks which were the sole defence on 19 February 1942. The concept of interception was to preferably shoot down the bombers before they arrived, and that often happened. So the bombs of those aircraft went into the sea with them. Bombers could also miss the target and have their ordnance fall into the ocean. Then again, a 2003 study of the waterfront area for unexploded ordnance during a 2003 redevelopment did not locate any bombs.[11]
It is often the case that bombs that end up in the water become deactivated, but it is not a certainty. Live ammunition from the Darwin shipwrecks from the war has sometimes been recovered, and still detonated. Some of this was the war stores in wrecks such as the freighters Mauna Loa and Meigs, both within Darwin Harbour, with their upper hulls recovered in 1959 by Fujita Salvage. Incidentally a lot of the ammunition from the ship defence guns which ringed Darwin in the war was taken outside the harbour in the early 1960s and disposed of at sea.
| In passing however, it should also be noted that unexploded ordnance is also sometimes found in downed Allied aircraft sites, not just those from enemy aircraft. There were hundreds of bombers operating out of northern Australia in the war, and sometimes they crashed after takeoff, joining the 62 Imperial Japanese Navy aircraft brought down in their raids.
Living in war-stricken areas means learning to live with such problems in a sensible way, not – as was the case with one enthusiastic explorer, causing such headlines such as “Australian man finds unexploded bomb, parades it around town on his truck for ‘show and tell’”.[12] |
Japanese WWII aircraft crashes in Northern Australia
Babs – 2 Betty – 17 Dinah – 9 Helen – 2 Jake – 4 Mavis – 1 Oscar – 2 Rufe – 2 Val – 2 Zero – 21 Total 62 Source: The Empire Strikes South, Tom Lewis, Avonmore Books, 2017. |
Finally, in another reason not to be too alarmed, not every unexploded bomb will detonate. The explosive may have become degraded. The firing system may have jammed. The bomb, although not going off, may have had its casing penetrated in impact and the explosive may have leaked. [13]
But it is foolhardy indeed to presume that any found aerial bomb – or indeed any war weapon such as a mortar round or a grenade – may be safe. There is only one thing to do upon finding such an item: note the location; retreat, and notify the right authorities through the police. These bombs were designed to kill, and they still often can. It’s likely there are several hundred more to be found around Darwin, and in closing it should be noted other raids target the rest of the NT coasts, and Western Australia and Queensland as well. It’s not so much as case of dial before you dig, as detect before detonation.
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Dr Tom Lewis OAM is a military historian. His recent books Bombers North and Eagles over Darwin provide extensive detail about Australia’s northern air war. His latest work is The Sinking of HMAS Sydney: “living, fighting and dying on WWII cruisers.”
[1] NT News. ”ADF bomb experts called to detonate 50kg WWII Japanese explosive at Darwin Waterfront.” https://www.ntnews.com.au/news/northern-territory/adf-bomb-experts-called-to-detonate-50kg-wwii-japanese-explosive-at-darwin-waterfront/news-story/2d98d572058b1b7902a2f66f0503c00c 26 Jun 2024.
[2] NT News. “Exclusion zone in place after divers locate unexploded bomb in Darwin Harbour.” https://www.ntnews.com.au/news/northern-territory/exclusion-zone-created-after-divers-locate-unexploded-bomb-in-darwin-harbour/news-story/77f458b42b1e721e6ebb751021ce9dfa 23 Sep 2022.
[3] ABC News. “World War II bomb unearthed by road construction crew near Darwin.” https://www.abc.net.au/news/2015-07-03/wwii-bomb-found-by-darwin-road-crew/6592766 3 July 2015.
[4] Other aircraft included a raid in June 1943 by 18 Helen and 9 Lily bombers, probably carrying the same load; scores of Dinah and Babs reconnaissance flights without bombs; and hundreds of Zero flights. The Zero could carry two 60kg bombs but the author has never seen a flight listing carrying any – the Broome attack for example utilized only the fighters’ cannon and machinegun armament.
[5] See Carrier Attack, by Tom Lewis and Peter Ingman, (Avonmore Books, 2013) for a full account of this.
[6] The author is grateful to Michael Claringbould, Military Aviation Historian, for his examination of the Kanoya Kokutai, the Betty record of flights.
[7] For example, “An estimated 10% of German bombs that were dropped during the war didn’t go off” according to an article about a Luftwaffe bomb in Plymouth, UK. Associated Press. “A World War II bomb prompted an evacuation in England before being taken to sea to be blown up.” 23 Feb 2024 https://apnews.com/article/bomb-britain-unexploded-wwii-plymouth-f46b89a68adf7e716cec91bcf718bceb
[8] British Broadcasting Corporation. “What do we know about unexploded WW2 bombs?” https://www.bbc.com/news/uk-england-devon-56243750 4 Mar 2021.
[9] Smithsonian Magazine. “There are still Thousands of Tons of Unexploded Bombs in Germany, left over from World War II.” https://www.smithsonianmag.com/history/seventy-years-world-war-two-thousands-tons-unexploded-bombs-germany-180957680/ Jan 2016.
[10] MechTraveller. “Who had the most reliable bombs in WW2?” https://mechtraveller.com/2018/03/who-had-the-most-reliable-bombs-in-ww2/ 16 Mar 2018.
[11] G-tek Project URSA03131 Waterfront Redevelopment Darwin, 2003. https://ntepa.nt.gov.au/__data/assets/pdf_file/0007/286684/appr.pdf
[12] Independent. “Australian man finds unexploded bomb, parades it around town on his truck for ‘show and tell’”. https://www.independent.co.uk/news/world/australasia/australian-man-finds-unexploded-bomb-parades-it-around-town-on-his-truck-for-show-and-tell-10473476.html 26 Oct 2015.
[13] MechTraveller. “Who had the most reliable bombs in WW2?” https://mechtraveller.com/2018/03/who-had-the-most-reliable-bombs-in-ww2/ 16 Mar 2018.
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