 Marlborough briefly served as the flagship for the deputy commander of the 4th Battle Squadron after King George V was damaged from striking a rock off <unk> . In November 1924 , the 4th Battle Squadron was renamed the 3rd Battle Squadron . In March 1926 , the 3rd Battle Squadron , including Marlborough , was transferred to the Atlantic Fleet . There , the battleships served as training ships . In 1929 , the ship 's 3 @-@ inch anti @-@ aircraft guns were replaced with more powerful 4 @-@ inch guns . In January 1931 , Marlborough served as the squadron flagship , relieving Emperor of India . She remained in the position for only five months , being decommissioned on 5 June . According to the terms of the London Naval Treaty of 1930 , the four ships of the Iron Duke class were to be scrapped or <unk> ; Marlborough was scheduled to be removed from service in 1931 and broken up for scrap . 
