“The artillery was arriving every minute; for Boyle, as usual far better than his word, had concentrated five ships on us in less than twenty-four hours. He put the monitor M.31, whose shallow draught fitted her for the job, in the end of the south-eastern creek of the harbour, whence she could rake the probable direction of a Turkish advance with her six-inch guns … The larger ships were moored to fire over the town at longer range, or to rake the other flank from the northern harbour. The searchlights of Dufferin and M.31 crossed on the plain beyond the town …

“… to reassure [the Arabs] fully they needed some sort of rampart to
defend, mediaeval fashion: it was no good digging trenches, partly
because the ground was coral rock, and, besides, they had no experience of trenches and might not have manned them confidently. So we took the crumbling, salt-riddled wall of the place, doubled it with a second, packed earth between the two, and raised them till our sixteenth-century bastions were rifle-proof at least, and probably proof against the Turkish mountain guns. Outside the bastions we put barbed wire, festooned
between cisterns on the rain catchments beyond the walls. We dug in
machine-gun nests in the best angles, and manned them with Feisal’s
regular gunners.”

Events of 5 to 10  December 1916 as recounted by T. E. Lawrence in Seven Pillars of Wisdom (1926).

Back in Yenbo, Lawrence watched as first Zeid and then Feisal’s army retreated into the town. With the Turks advancing, the
defence of Yenbo became a priority.

Lawrence liaised with Captain Boyle of the Red Sea Patrol to
provide Naval support, while the task of erecting defences was led by the explosives expert Major Garland, who had been in the Hejaz to provide training to the Arabs.

“Nearly everyone sat up that night,” wrote Lawrence, as the Turks drew near on the 11th.