Wang Changling was praised as the "Seven Wonders" by later generations. Please analyze the mystery of his writing with the specific poems in Join the Army.

Among frontier poets, Wang Changling wrote the most and the best. His group poem "Join the Army" is almost all excellent, revealing the psychological activities of frontline soldiers from all angles. For example, the fourth:

There is a dark snow-capped mountain in Qinghai, with long white clouds and a lonely city looking at Yumenguan. Yellow sand wears golden armor in hundreds of battles, but the loulan is not returned.

Qinghai is overcast with war clouds, and the snow-capped mountains stretch for thousands of miles, rendering the atmosphere of war full and hearty; "Yellow Sand Wearing Golden Armor and Winning Every Battle" not only reveals the hardships of the environment, but also shows the heroic spirit of the soldiers who went into battle lightly and made Qiang Bing rich.