What are the battle scenes described in the poem "Wild Goose Gate's Taishouxing"?

The poem that exaggerates the tragic atmosphere of war in "A Trip to the Wild Goose Gate" is: The horn is ringing all over the sky in autumn, and the swallows are full of purple at night.

This poem and sentence have distinct colors. Such as gold, rouge and purple, are not only bright, but also rich. They are intertwined with black, autumn and jade white, forming a colorful picture. A poet, like a talented painter, is particularly good at coloring, expressing things with color and moving people with color, not just sketching the outline. When he writes poems, he seldom uses line drawing, but always uses imagination to describe them with various novel and strong colors, which effectively shows their multi-level nature.

The dark clouds above the city are a metaphor for the arrogance of the enemy, and the shining light of the sun shows the heroic spirit of the soldiers guarding the city, with bright colors and clear love and hate.