The seventy sandbags of "sacred soil" are a central part of the Flanders Field Memorial Garden, being created at Wellington Barracks to mark next year's 100th anniversary of the start of the war.
Tomorrow the sandbags will be loaded on to a gun carriage of the King's Troop Royal Horse Artillery. A casket, symbolically containing a crucible of soil from all the battlefields, will be piped ashore from HMS Belfast and placed with the bags on the gun carriage before departure.
The 1.5 ton carriage, drawn by six colour matched black Irish draught horses will cross Tower Bridge and into the City of London, and pass by landmarks such as St Paul's Cathedral and Buckingham Palace on the way to Wellington Barracks.
The garden has been designed by Belgian architect Piet Blanckaert and will be opened officially on Remembrance Sunday 2014.