Life at the front - Horses did much of the dirty work. From the era of gun and cannon on certainly with the onset of "modern" warfare (19th C on) horses were literally worked to death even when they were not actively killed by gunshot/artillery fire--having insufficient food and little or no shelter contributed to the terrible attrition. SHAME ON US!!!
Big Bertha was a large howitzer used by the Germans in WW1. It could hurl a 1 ton shell 8 miles. 12 were made during the war and they destroyed many French forts, terrifying the French when they fired. The gun was named after the heiress to the Krupp fortune. It weighed 43 tons with its tractor and required many men and much time to move and prepare. Two survived the war. One came to the US and was melted down in 1950; the other was used by the Germans in WW2. No one knows what became of it.
Since the Fire Nation focused a war of attrition on the Southern Water Tribe, severely depleting their number and taking all their benders, it's not at all surprising that the men would wear Northern Water Tribe colours and symbols - to draw unwanted attention away from home.
https://flic.kr/p/5hXGdz | The Horror of War | Dead North Vietnamese Army (NVA) soldiers about to be buried. They were killed in a battle near An Khe in the Republic of South Vietnam. These were worthy adversaries that we had to respect. Remember, they defeated the most powerful nation on earth in a war of attrition.