The Ordnance BL 15-inch howitzer was developed by the Coventry Ordnance Works late in 1914 in response to the success of its design of the 9.2-inch siege howitzer.

The howitzer was cumbersome to deploy, since it was transported in several sections by giant Foster-Daimler tractors.

The weapon was operated by Royal Marine Artillery detachments of the Naval Brigade, with one gun per battery.

It operated successfully where it was needed to destroy deep fortifications on the Western Front, but was limited by its relatively short range compared to other modern siege howitzers.

The size and weight made it difficult to move and emplace.