"They're giving their friends a taste of their own pills," replied Dick. "It's great! They've mistaken the troops for our men."

Such indeed was the case, for the search-light was slowly yet surely following the retreating, panic-stricken Turkish soldiers, while shell after shell hurtled towards the fugitives as fast as the gun could be discharged.

Suddenly came the report of a double concussion—so quickly that the detonations sounded as a single crash. Then came another.

"By Jove! The skipper is tackling the patrol-boat with our little anti-aircraft gun!" exclaimed Farnworth.

Once more the midshipman was right in his surmise. Taking advantage of the darkness, rendered doubly baffling to the Turks on the patrol-boat owing to the contrast afforded by the search-light, the Lieutenant-Commander of "E—" had boldly brought his craft within close range of the enemy craft.

He knew the risk. One shot from the Ottoman quick-firer would send the submarine to the bottom like a stone. On the other hand, the patrol-boat was nothing more than an old iron tug, on which a light quick-firer had been mounted. Formidable enough when operating against troops unprovided with guns, the Turkish craft was vulnerable even to the smallest quick-firer.

Taken completely by surprise as the first British shell played havoc with her bridge and search-light projector, the patrol circled in a vain endeavour to escape. A second shell ripped a large hole in her water-line, causing her to reel violently and commence to list heavily to starboard.

Only once did the patrol-boat attempt to reply to the devastating shell-fire of the submarine: but the missile, hastily and badly aimed, flew wide, exploding a couple of thousand yards away.

Huxtable's reply was to send a shell crashing against the frail shield of the Turkish gun. The explosion did its work thoroughly, for the gun crew were wiped out and the weapon dismounted.

Twenty seconds later, so destructive had been the effect of the shell upon the compartmentless hull of the craft, the patrol-boat disappeared beneath the surface, her boilers exploding with tremendous violence as she did so.