Obice 305/17
The Obice da 305/17 was the Italian army’s giant hammer, a super-heavy howitzer built to smash forts, coastal targets and deeply dug-in positions. In service during both world wars, it was one of the most powerful guns the Regio Esercito ever fielded, and it enjoyed a surprisingly long career for such a specialised weapon.
Its story began in 1908, when Italian coastal artillery officers, studying the lessons of the Russo-Japanese War, decided their old 280 mm Armstrong pieces were no longer up to the task. They wanted something bigger, more accurate and far more destructive. Several major firms submitted designs, but in the end the choice fell on the Armstrong-Pozzuoli works near Naples, an Italian subsidiary of the British Armstrong company. With some requested changes to ammunition handling, armour protection and loading arrangements, the design evolved into what became the Obice da 305/17.
The gun was ultimately manufactured by Armstrong-Pozzuoli and also by Vickers-Terni. Production ran from the early stages of the First World War until 1917, and because these were enormous, specialised weapons, they were never made in large numbers. Estimates vary, but only somewhere around thirty to forty-odd guns were produced, making each one a valuable asset.
Its designation tells you quite a bit. The 305 refers to its calibre in millimetres, roughly 12 inches. The 17 refers to the barrel length in calibres, measured without the breech. In practice the whole barrel-and-breech assembly was closer to 19 calibres long. The rifled steel barrel was about 5.8 metres in length with sixty grooves, and the barrel and breech together weighed nearly 13 tonnes. Fully assembled on its platform or carriage, the system could exceed 30 tonnes, and a crew of around ten men was usually required to operate it.
Technically, the howitzer combined sheer size with clever engineering. It used a hydro-pneumatic recoil system in which hydraulic cylinders absorbed most of the kick when fired, while compressed gas pushed the barrel back into battery. The breech was an interrupted-screw type, strong and reliable. The gun sat in a cradle on a substantial carriage that allowed very high angles of elevation and provided room for the massive recoil travel.
Ammunition was separate-loading, with the shell and the bagged propellant charges handled individually. Given the size of the projectiles, this was really the only practical method. Shells weighed between about 295 and 442 kilograms, depending on type. High-explosive and concrete-piercing shells were the most common, meant for bringing down fortifications, coastal structures and heavy bunkers. The variable propellant charges allowed crews to tailor the range and the arc of fire.
At full charge, the gun could hurl a shell to around 17.6 kilometres. Its muzzle velocity was about 545 metres per second. Rate of fire was very slow by ordinary artillery standards: perhaps one round every five minutes at best, and more commonly one every ten or twelve minutes. But when every shot was the size of a small car engine and capable of demolishing concrete structures, volume mattered less than impact.
Originally the 305/17 was intended as a coastal defence howitzer. One of the first versions sat on a fixed metal platform designed by General Garrone, which allowed full 360-degree traverse. These coastal batteries began entering service in 1914 at major Italian naval bases and strategic straits.
When Italy entered the First World War, the army urgently needed heavy siege artillery for mountain warfare and the Isonzo front. Engineers quickly worked out ways to move the gun overland. The Modello 1916 and Modello 1917 versions were transportable, though only in several enormous loads: barrel and cradle, recoil system, upper carriage and platform. These were dragged into position by powerful tractors, and assembling the entire firing platform could take a full day of tough, coordinated labour.
The most distinctive version was the one mounted on the De Stefano carriage. This four-wheeled box-trail assembly looked almost like a giant toy horse on wheels. It could be towed in one piece by a heavy Pavesi-Tolotti tractor. In firing position, the wheels rested on inclined steel rails laid on a wooden platform. When fired, the recoil lifted the gun carriage up the rails and gravity then let it roll back into firing position. It was an ingenious, almost eccentric system that allowed the gun to fire without digging massive pits.
In the First World War the Obice 305/17 served as siege artillery, battering strongpoints, mountain fortifications and hardened positions. Several guns were captured during the Italian retreat after Caporetto in 1917, a reminder of how difficult they were to move under pressure.
A handful had a second life in Spain during the Spanish Civil War, where five were supplied to the Nationalist forces. On the eve of the Second World War, Italy still had a modest number in service. They saw use in frontier artillery during the 1940 campaign against France and later as coastal defence weapons in places like Naples and Sicily. The Italian navy’s coastal artillery branch also operated some in shielded mounts. Remarkably, a few examples remained in service well after the war, with final retirement coming around 1959.
Because so few were built, many guns developed a sort of individual identity. Photographs show them trundling along roads on their bizarre carriages or looming over small mountain valleys. Crews took pride in them, despite the hard work involved: everything was heavy, every step required teamwork, and every shot demanded careful preparation. Slow-firing though they were, their shells could crush concrete, obliterate bunkers and reshape entire stretches of battlefield.
