10.5-cm Kanone 18 and 18/40
Among the post-war requirements for a new German artillery park to replace the lost relics of World War I was that for a new long-range gun for use by corps rather than field artillery batteries. This project was one of the very first put out to the underground German armaments industry, for by 1926 both Krupp and Rheinmetall had produced specimen designs and by 1930 both were ready with prototype hardware.
As it turned out the German army could not decide which design to approve; in the end it compromised by accepting the Rheinmetall barrel and the Krupp carriage. The Krupp carriage was destined to become one of the most widely used of all the German artillery carriages, for it was the same as that used on the larger 15-cm sFH 18 howitzer series. It was 1934 before the first guns actually reached the troops and for a while the new gun, known as the 10.5-cm K 18 (Kanone, or gun), was the standard weapon of the medium artillery batteries.
This state of affairs did not last long for the choice of 105-mm (4.134-in) calibre for a medium gun was to prove an unhappy one. In a nutshell the gun was too heavy for the weight of projectile fired. The larger 150-mm (actually 149 mm/5.87 in) howitzers fired a much more efficient projectile over almost the same range and at no great increase in weapon weight. There was also another snag: when the K 18 entered service it was at a time when the German army had yet to become even partially mechanized, so the guns had to be pulled by horse teams. The gun weighed too much for one horse team to tackle, so the barrel and carnage had to be towed as separate loads, which was a bit much for a 105-mm (4,13-in) gun, Later on the introduction of half-tracked tractors enabled the piece to be towed in one load, but by then the K 18 was on a very low production priority.
In order to make the K 18 a more powerful weapon, the German staff planners called for an increase in range. There was no way to produce this increase without lengthening the length of the barrel from the original IV52 to IV60. The first of these improved models was ready in 1941 and was known as the 10.5-cm K 18/40, but it was not put into production until much later when the designation had been changed yet again to 10.5-cm sK 42 (schwere Kanone, or heavy gun). Very few were actually produced.
By 1941 the disadvantages of the K 18 and its later versions had been recognized, but there remained a role for them where their weight and bulk would be of a relatively minor disadvantage, namely coastal defence. Weapons for the Atlantic Wall, at that time still under construction, were in great demand and short supply, so the K 18 was assigned to that relatively static role. As a coastal defence weapon the piece had a considerable advantage in its long range, even if the projectile weight was still rather low. To enable it to be used to greater advantage when firing at marine targets a new range of ammunition was introduced, among which was a special sea marker shell for ranging purposes.
Specification 10.5-cm K 18
Calibre: 105 mm (4.134 in)
Length of piece: 5.46 m (214.96 in)
Weight: travelling 6434 kg (14,187 lb) and in action 5624 kg (12,400 lb)
Elevation: -0° to +48°
Muzzle velocity: 835 m (2,740 ft) per second
Range: 19075 m (20,860 yards)
Shell weight: 15.14 kg (33.38 lb)