Definition of hoist one's flag in English:
hoist one's flag
phrase
(of an admiral) take up command.
‘In 1814 he briefly hoisted his flag at sea, commanding the naval escort for Louis XVIII's return to France from his English exile.’- ‘Before their plans could come to fruition, though, they had a serious falling out, and on 2nd September 1966 he and his family took control of the tower on their own and hoisted their flag.’
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