Article 10 and the replacement clock

Article 10 made treaty administration more than a headline tonnage figure. Within one month of laying down or completion, a state had to tell every other signatory the vessel's classification, standard displacement in imperial and metric tons, principal dimensions, mean draught, and largest gun calibre. The annex then tied replacement to the laying-down date. A cruiser laid down before 1 January 1920 became replaceable after sixteen years, while one laid down after 31 December 1919 had to wait twenty. A technical date in a ship's history therefore controlled when a navy could modernise its force.