Virtual
War Memorial
Australia

Medium Trench Mortar Batteries

This is a generic listing to cover personnel listed in the Embarkation Roll as having been assigned to Medium Trench Mortar reinforcements.

The ANAZACs at Gallipoli had little in the way of artillery and virtually no Trench Mortars, and certainly not in any formal structure.

After the 'doubling of the AIF' in Egypt, following the withdrawal from Anzac, mortars were incorporated at Brigade (Light Trench Mortar Batteries), at Division (Medium and Heavy Trench Mortar Batteries) and at Corps level (Heavy Trench Mortar Batteries).

Each Division had several batteries of Medium and Heavy Trench Mortars  - see the respective listing for more information.  Men assigned to them had been allocated to the Royal Australian Artillery.  On arrival in the UK, they would pass through Training Schools and then be deployed for service to the Western Front.

Men in these reinforcement drafts would have ended up in one of the following.  Their Service Record needs to be consulted to identify the correct

1st (Divisional) Medium and Heavy Trench Mortar Batteries, AIF (/explore/units/469)

2nd (Divisional) Medium and Heavy Trench Mortar Batteries, AIF (/explore/units/455)

3rd (Divisional) Medium and Heavy Trench Mortar Batteries, AIF (/explore/units/1033)

4th (Divisional) Medium and Heavy Trench Mortar Batteries, AIF (/explore/units/472)

5th (Divisional) Medium and Heavy Trench Mortar Batteries, AIF (/explore/units/451)

Heavy (Corps Artillery) Trench Mortar Batteries (/explore/units/373)

The Battle of the Somme ended in November 1916, and the British and Empire Armies started rebuilding for the campaigns of 1917.  The Stokes 3-inch mortar provided a valued capability because of their high looping trajectory.  This meant that the bombs fell almost vertically onto the target and could reach into trenches and field defences that conventional guns could not.

The early Stokes (light) mortars underwent progressive improvement.  Improved propellants for the 3 and 4-inch Stokes and a new medium mortar were introduced.  The 4 inch weapon became a specialist chemical mortar not used by Australian troops and is not considered further.

In the autumn of 1916 a Major Newton developed the use of extra charge rings that slipped over the rear of the bombs that enabled the range of the 3-inch Stokes mortar to be extended to 677 metres. Further improvements in the charge rings saw the range extend to 754 metres and by the beginning of 1918 the 3-inch Stokes could range to 1,143 metres.

This was the maximum range that could be obtained using the odd-looking cylindrical bomb, which lacked the fins that came to characterise mortar bombs.  The cylindrical bomb had a poor drag coefficient which with the mortar barrel's maximum chamber pressure of two tons per square inch were the key limiting factors in achieving greater range.

Major Newton also developed a new medium mortar that used the same firing system as the Stokes mortar. This became the 6-inch Trench Howitzer Mark I, commonly known as the ‘Newton’ or ‘Stokes-Newton’. The design was successful with 1,700 being ordered in late January 1917. Deliveries began in May, and in June the ammunition started arriving in France. In 1917 1,929 Newton mortars were produced with a further 609 in 1918 with ammunition production 239,471 and 1,134,805 rounds respectively. 

The 6-inch mortars replaced the 2-inch medium mortars, known as 'Toffee Apples' because of their distinctive 'overbore' bomb.  The 6-inch mortars had not completely replaced the 2-inch mortars by the beginning of 1918.

The mortar weighed 189 kilograms in action in action and fired both 35 kilogram steel and 25 kilogram iron bombs. Both bombs contained 10 kilograms of high explosive. The steel bomb had a minimum range of 460metres and a maximum range of 950 metres and the iron bomb had a minimum range of 90 metres and a maximum range of 1278 metres with a maximum effective range due to dispersion of 1,000 metres.

We would particularly like to encourage individual historians researchers or members of unit associations to contribute to the development of a more detailed history and photographs pertaining to this unit and its members.

Please contact [email protected] (mailto:[email protected]) for details on how to contribute.