until the armistice was signed was any escort force strong enough to insure entire safety. If we had had destroyers enough to put a close screen, or even a double screen, around every convoy, there would have been almost no danger from submarines. The fact that all escort forces were very inadequate placed a very heavy responsibility upon the escort commanders, and made them think twice before detaching a destroyer in order to protect stragglers. One late summer afternoon the American converted yacht _Christabel_ was performing this duty for the British merchantman _Danae_, a vessel which had fallen eight miles behind her convoy, bound from La Pallice, France, to Brest. It was a beautiful evening; the weather was clear, the sea smooth, and there was not a breath of wind. Under such conditions a submarine could conceal its presence only with great difficulty; and at about 5.30 the lookout on the _Christabel_ detected a wake, some six hundred yards on the port quarter. The _Christabel_ started at full speed; the wake suddenly ceased, but a few splotches of oil were seen, and she was steered in the direction of this disturbance. A depth charge was dropped at the spot where the submarine ought to have been, but it evidently did not produce the slightest result. The _Christabel_ rejoined the _Danae_, and the two went along peacefully for nearly four hours, when suddenly a periscope appeared about two hundred yards away, on the starboard side. Evidently this persistent German had been following the ships all that time, looking for a favourable opportunity to discharge his torpedo. That moment had now arrived; the submarine was at a distance where a carefully aimed shot meant certain destruction; the appearance of the periscope meant that the submarine was making observations in anticipation of delivering this shot. The _Christabel_ started full speed for the wake of the periscope; this periscope itself disappeared under the water like a guilty thing, and a disturbance on the surface showed that the submarine was making frantic efforts to submerge. The destroyer dropped its depth charge, set to explode at seventy feet, its radio meantime sending signals broadcast for assistance. Immediately after the mushroom of water arose from this charge a secondary explosion was heard; this was a horrible and muffled sound coming from the deep, more powerful and more terrible than any that could have been caused by the destroyer's "ash can." An enormous volcano of water and all kinds of débris arose from the sea, half-way between the _Christabel_ and the spot where it had dropped its charge. This secondary explosion shook the _Christabel_ so violently that the officers thought at first that the ship had been seriously damaged, and a couple of men were knocked sprawling on the deck. As soon as the water subsided great masses of heavy black oil began rising to the surface, and completely splintered wood and other wreckage appeared. In a few