“Go,” she whispered, “go, and God bless you!  Go even though it be to death!  Their airmen will take toll of some of the attackers, Gabriel.  Not all the Comrades will return.  Oh, may you—­may you!”

“What is written on the Book of Fate, will be,” he answered.  “Our petty hopes and fears are nothing, Catherine.  If death awaits me, it will be sweet; for it will come, tonight, in the supreme service of the human race!  Good-bye!”

With a sudden motion, the girl took his face between her hands, and kissed his forehead.  For all her courage and strength, he sensed her heart wildly beating and he felt her tears.

“Good-bye, Gabriel,” she breathed.  “Would I might go with you!  Would that my duty did not hold me here!  Good-bye!”

Then he was gone, gone with the others, into the thickening obscurity of the fog-shrouded evening.  Now Catherine stood there alone, head bowed and wet face hidden in both hands.

As the little fighting band disappeared, back to the girl drifted a few words of song, soft-hummed through the dusk—­the deathless chorus of the International: 

    “Now comes the hour supreme! 
    To arms, each in his place! 
    The new dawn’s International
    Shall be the human race!...”

CHAPTER XXXIV.

THE ATTACK.

“Halt!  Who goes there?”

The challenge rang sharply on the night air, outside a small gate in the barricade of the Monck Aviation Grounds.

“Liberty!” answered Gabriel, pausing as he gave the password.

“All right, come on,” said a vague figure at the gate.  The little group approached.  The gate opened.  Silently they entered the enclosure.

Another man stepped from a hangar.  In his hand he held an electric flash, which he threw upon the newcomers, one by one.

“Right!” he commented, and took Gabriel by the hand.  “This way!”

Ten minutes later, all of them were in the air, save only Gabriel, who insisted on staying till his entire squad had made a clean getaway.  Then he too rose; and now in a long, swift line, the fighting squadron straightened away to north-eastward, on the twenty-mile run to Niagara.

The night was foggy, chill and dark.  All the aviators had instructions to fly not less than 2,500 feet high, to keep a careful lookout lest they collide, and to steer by the lights of the great Air Trust plant.  For, misty though the heavens were, still Gabriel could see the dim glow of the tremendous aerial search-lights dominating Goat Island—­lights of 5,000,000 candle-power, maintained by current from the Falls, incessantly sweeping the sky on the lookout for just such perils as now, indeed, were drawing near.

Momently, as he flew, Gabriel perceived these huge lights growing brighter, through the mist, and apprehension won upon him.

“Incredibly strong!” he muttered to himself, as he glanced from his barometer to the shining fog ahead.  “Even though the mist will be thicker over the Falls than anywhere else, there’s a good possibility they may pierce it and pick us up—­and then, look out for their ’planes and swift, fighting dirigibles!”