Sentence:  For observe, it was an assemblage of two hundred thousand "young" men—not simpering, dainty, kid-gloved weaklings, but <WSD>stalwart</WSD>, muscular, dauntless young braves, brimful of push and energy, and royally endowed with every attribute that goes to make up a peerless and magnificent manhood—the very pick and choice of the world's glorious ones. 
Meaning of the word marked with <WSD> tags:  Firmly or solidly built.