Merchant ships were to be disarmed according to the Weekly Intelligence Summary No. 15 for the week ending 29 March 1919

An item reported that at the date of the Armistice 4,203 merchant ships received a defensive armamement, since then were up to 29 March 2,184 ships disarmed. On 15 December 1918 were 11,343 D.A.M.S. ratings borne, of whom since then 8,568 were discharged or dispersed.

Source

The National Archives, Kew Gardens, England CAB-24-77-68