On 14 March 1840 Cumming was appointed mate on the frigate HMS "Cyclops" (commanded by Horatio Thomas Austin), part of Commodore Charles John Napier's squadron sent to intervene for Britain in the Syrian War, and reached the ship in April. The war had begun when Mehemet Ali, Pasha of Egypt, attempted to claim independence from the Ottoman Empire. Ali invaded Syria and took control of the Ottoman Fleet forcing young Sultan Abdülmecid I to request help from the European powers. Great Britain, Austria, Prussia and Russia agreed to assist and issued an ultimatum to Ali demanding his withdrawal from Ottoman possessions (Arabia, Crete and Syria) in return for being made hereditary Viceroy of Egypt. "Cyclops" was detached from patrolling to carry the ultimatum into Alexandria on 9 August 1840.