Now, God be thanked Who has matched us with His hour,
And caught our youth, and wakened us from sleeping,
With hand made sure, clear eye, and sharpened power,
To turn, as swimmers into cleanness leaping,
The poem’s opening may bring to mind a prayer or a church sermon. The declarative “Now”, draws the reader’s attention. God is to be thanked for this opportunity for young people to demonstrate their patriotism. “His hour” is, of course, the call to arms. 
 In terms of rhythm, the line has a solid, emphatic beat, following almost perfectly the  iambic pentameter  metre appropriate to a sonnet.
Peace