It was indeed true. With the control of the skies assured us, our fleet of liquid gas carriers had now gone into action and at many points we saw the heavy poison clouds spreading over the enemy hosts like a yellow green sea. The battle of chlorine had begun. The war of chemistry was raining down out of the skies. It is certain that nothing like this had ever been seen before. There had been chlorine fighting in the trenches out of squirt gun apparatus--plenty of that in 1915, with a few score killed or injured, but here it came down by tons over a whole army, this devilish stuff one breath of which deep into the lungs smote a man down as if dead. The havoc thus wrought in the German ranks was terrific; especially as General Wood took advantage of the enemy’s distress to sweep their lines with fierce artillery fire from his batteries on the heights. “We’ve got them going,” said I. Berg shook his head. “Not yet.” If General Wood had been able to hurl his army forward in a desperate charge at this moment of German demoralisation it is possible we might have gained a victory, but the risks were too heavy. The American forces were greatly outnumbered and to send them into those chlorine-swept areas was to bring the enemy’s fate upon them. Wood must hold his men upon the heights until our artillery and poison gas attack had practically won the day. Then a final charge might clinch matters--that was the plan, but it worked out differently, for, after their first demoralisation, the enemy learned to avoid the descending danger by running from it. They could avoid the slowly spreading chlorine clouds by seeking higher ground and, presently, they regained a great measure of their confidence and courage and swept forward in furious fresh attacks. Even so the Americans fought for hours with every advantage and our artillery did frightful execution. At three o’clock I sent off a cable to the _Times_ that General Wood’s prospects were excellent, but at half-past four our supply of liquid chlorine was exhausted and news came from Niagara Falls that a German spy on Grand Island had blown up the great chlorine supply tank containing 20,000 tons. And the Niagara power-plants had been wrecked by dynamite. Still the Americans fought on gallantly, desperately, knowing that everything was at stake, and our aeroplanes, with their batteries of machine guns, gave effective assistance. Superiority in numbers, however, soon made itself felt and at five o’clock the Germans, relieved from the chlorine menace, advanced their heavy artillery and began a terrific bombardment of our trenches. “Hello!” exclaimed Berg suddenly. “What’s that coming?”