The memorials, one for the First World War and one for the Second, commemorate civilian, merchant seafarers and fishermen who were killed as a result of enemy action and have no known grave.

The first memorial was commissioned in light of the heavy losses sustained by merchant shipping in the First World War—more than 17,000 people died and some 3,300 British and Empire-registered commercial vessels sunk as a result of enemy action.

A compromise was struck, as a result of which the memorial was constructed in Trinity Square Gardens on Tower Hill, a site further from the river but with a long maritime history.

Maufe designed a sunken garden, accessed by steps behind the original memorial, the walls of which were again clad with bronze panels with the names of the missing.

Lutyens acted as an unpaid advisor to the IWGC during the war, in which capacity he made several visits to France to make initial plans for organised cemeteries.

[1][2][3][4] The IWGC and its founder, Fabian Ware, were determined from the outset that all casualties should be individually and equally commemorated, regardless of military rank or social status.

Where it was not possible to provide a headstone (for example because a body could not be recovered), a casualty's name was included on one of the commission's large memorials, such as Tower Hill.

[5][6] The commission's charter defined its scope as "members of the military and naval forces of the Crown"; in 1921 the commissioners resolved that this extended to the Mercantile Marine and other civilian organisations who were engaged in the war effort.

Merchant ships were regularly sunk by the German Navy from the outset of the war, particularly after Germany commenced unrestricted submarine warfare.

This was approved by London County Council, but the Office of Works rejected it on the advice of the Royal Fine Arts Commission (RFAC), which objected on two grounds: first, that Lutyens' proposal would involve the demolition of an arch built when the Thames Embankment was constructed; and second, that the memorial would be better suited to a site further downstream, east of Tower Bridge, where it would be seen by ocean-going vessels which could not travel west of the bridge.

The bill was laid before Parliament in December 1926 and received royal assent in June 1927, becoming the Mercantile Marine Memorial Act 1927 (17 & 18 Geo.

The building work was undertaken by Holloway Brothers (London) and the memorial was unveiled by Queen Mary (deputising for her husband, King George V) on 12 December 1928, her first solo engagement of the sort.

The attic is similar to Lutyens' original design for the York City War Memorial, which featured a Stone of Remembrance rather than a drum.

[1][17][9][18][19] The memorial's main dedication is in bronze letters to the front (south) of the attic: TO THE GLORY OF GOD AND TO THE HONOUR OF TWELVE THOUSAND OF THE MERCHANT NAVY AND FISHING FLEETS WHO HAVE NO GRAVE BUT THE SEA; above it are the dates of the First World War (1914–1918), which are also carved into the stone on north side.

[25] The resemblance to the cemetery buildings is also noted by the Dutch architect Jeroen Geurst, who compares it in particular to those at Hooge Crater in Belgium and Serre Road in France.

[26] In the opinion of the historian David Crane, the memorial never recovered from its "miserable start" and is consequently the least well-known of the IWGC's major works following the First World War.

[6] From the outbreak of the Second World War, shipping losses were again high and a similar convoy system was used in an effort to protect merchant vessels.

[17][28][29][30] Following the Second World War, the IWGC considered various sites for a memorial to the new casualties but, after consultation with the relevant public bodies, decided Tower Hill was the most appropriate location.

The commission briefed Maufe that the new memorial should complement Lutyens' design and fit in with the existing architecture in the area, including the Port of London Authority building.

Maufe initially planned a larger grassy area between Lutyens' colonnade and the sunken garden with a Stone of Remembrance at the centre.

[31][32] The memorial commemorates merchant seamen from ships registered in Britain or its Empire or on loan to the governments of those countries, and who were lost at sea as a result of enemy action in the Second World War; it lists 23,765 men, of whom 832 were fishermen and 80 maritime pilots and lighthousemen.

The ceremony, described by The Sunday Times as "all as modest and anonymous as the Merchant Navy itself", concluded with the sounding of the "Last Post" by buglers from the Royal Marines, answered by a single ship's horn on the River Thames.

Each of the flanking pylons supports an over-life-sized statue, representing a Merchant Navy sailor (on the east side) and officer (on the west).

[43] After the Second World War, a three-volume Roll of Honour of the Merchant Navy and Fishing Fleets 1939–1945 was produced in 1958 by the Ministry of Transport and Civil Aviation and distributed to a range of organisations in the UK and abroad.

Around the base are bronze plaques, one of which contains the inscription IN MEMORY OF THOSE MERCHANT SEAFARERS WHO GAVE THEIR LIVES TO SECURE THE FREEDOM OF THE FALKLAND ISLANDS 1982.

The Falklands memorial, which is not listed, was unveiled on 4 September 2005 by the First Sea Lord, Admiral Sir Alan West and is maintained by the Commonwealth War Graves Commission (the IWGC having changed its name in 1960).

It was upgraded to grade I status (which is applied to around 2.5% of listed buildings, those of "the greatest historic interest") in November 2015 when Lutyens' war memorials were declared a national collection.