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Bob Semple Tank

Tractor-Tank Prototype [ 1942 ]

Underpowered, cumbersome and ungainly - the Bob Semple Tank was born out of sheer desperation for New Zealand during World War 2.

Authored By: Staff Writer | Last Edited: 12/28/2018 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

At the start of World War 2 (1939-1945), New Zealand joined its neighbor Australia in recognizing that neither power held a viable arms-producing industry - particularly where tanks and related armored vehicles were concerned. When it became apparent that these systems would not be arriving from Britain or the United States any time soon, and under threat from an ever-expanding Imperial Japanese sphere in the Pacific, both countries began to seek solutions from within their respective borders. Several endeavors resulted in now-overlooked contributions to World War 2 land-based warfare - some useful, others quite forgettable - and one key example of the latter became the "Bob Semple Tank" to come out of New Zealand.

The tank was named after Bob Semple, the then-acting Minister of Works, who championed the idea of an indigenous New Zealand tank to defend the country from land invasion by Japanese forces. The tank was hastily arrange around a Caterpillar D8 bulldozer which had been in production since 1935. To this was added a crude, corrugated-finish metal superstructure intended to protect the operating crew from small arms fire. A lack of available heavy-caliber weaponry meant that the vehicle carried only machine guns - 6 x 0.303 inch BREN types - and these were set along each primary hull facing - one at each side, a pair facing forward, one to the rear and a sole fitted to the traversing turret. At the very least this would offer some firepower against enemy infantry at range.

The work produced a crude, almost comical, machine that featured a crew of eight stuffed into a cramped fighting compartment that also held the original tractor's powerplant and gearbox as well as ammunition stores for the guns. The hull superstructure did sport a turret and the vehicle relied on a track-and-wheel arrangement that gave it basic qualities to identify the machine as a "tank" but the vehicle was hardly a combat-worthy offering. Power came from the original Caterpillar 6-cylinder diesel outputting around 127 horsepower which led to limited road speeds to a pedestrian 15 miles per hour in ideal conditions and operational ranges out to 100 miles.

It was quickly realized that the vehicles were too slow and ponderous to be of any tactical value. Gear-switching required the tank to come to a complete stop before changing could occur and accurate fire from the rocking hull was less-than-ideal. Additionally armor protection was lacking on the whole and the vehicle proved inherently underpowered while the vehicles stood some twelve feet tall. All this, coupled with the fact that there were no formal plans written up for building subsequent Bob Semple Tanks to any particular standard, led to the "tractor-tank" approach being quickly abandoned and only a handful of vehicles came out of Christchurch before these were inevitably returned to their previous state as industrial tractors.

Despite this failure, at the heart of the Bomb Semple Tank initiative lay the determined nature of New Zealand to offer up its own defense through sheer ingenuity coupled with a layer of desperation. By using local resources and workshops to accomplish the task, the available tractors were to be quickly converted to fighting form where and when needed and sent to harass enemy forces attempting to gain a foothold in the country. Fortunately for the twin-island nation, World War 2 was never fought on New Zealand soil and any Japanese attempt to take Australia was eventually thwarted by Allied actions in the Pacific Theater - leading the Bob Semple Tank to fall to the pages of military history.©MilitaryFactory.com
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Ministry of Works (Temuka) - New Zealand
New Zealand (cancelled)
Operators National flag of New Zealand
Service Year
New Zealand
National Origin

Support allied ground forces through weapons, inherent capabilities, and / or onboard systems.
Engage armored vehicles of similar form and function.

13.8 ft
(4.2 meters)
10.8 ft
(3.3 meters)
12.0 ft
(3.65 meters)
55,997 lb
(25,400 kg)
28.0 tons

1 x Caterpillar 6-cylinder diesel engine developing 127 horsepower.
Drive System
15 mph
(24 kph)
Road Speed
99 miles
(160 km)
Road Range

1 x 0.303 caliber BREN medium machine gun in turret
2 x 0.303 caliber BREN medium machine guns (forward-facing).
1 x 0.303 caliber BREN medium machine guns in left hull side.
1 x 0.303 caliber BREN medium machine gun in right hull side.
1 x 0.303 caliber BREN medium machine gun (rear-facing).
Not Available.

"Bomb Semple" - Base Series Name; no more than five examples completed.

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Image of the Bob Semple Tank
Image from the Public Domain.

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