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Distinguished Service Order (DSO) Number awarded to O.B.s - 4 (Lumsden with 3 bars) The (DSO) is a United Kingdom military decoration. It was awarded for meritorious or distinguished service by officers during wartime, generally in armed combat or under fire. Typically it was awarded to officers of rank Major or higher. However, it has been awarded to a number of particularly valorous junior officers. On these occasions it was often taken that they had only just missed being award the Victoria Cross. Throughout the First World War, 8981 DSOs were awarded. Established: 6 September 1886 by Queen Victoria. Form: The medal was in the form of a gold cross, enamelled white with gold edging. The centre features a green enamelled laurel wreath, emblazoned with the Imperial Crown. The back is engraved with the Royal Cypher.
Source: https://assets.digital.cabinet-office.gov.uk/ government/uploads/system/uploads/image_data/ file/4495/Distinguished_Service_Order.jpg
Unusually, the ribbon featured a bar at the top, as well as at the bottom. A gold bar featuring the Crown would be issued to holders who earned a second DSO. The bar would be engraved with the year of issue.