Why did veterans march on washington dc in 1932?

The Bonus Army was the popular name for an assemblage of some 43,000 marchers 17,000 US World War I veterans, and their families, and affiliated groups who gather in Washington DC in the summer of 1932 to demand a cash payment redemption of their service certificates.

In the midwest because it has more moderate climate than the north or south west which makes farming far easier.

Do you have more info about it ? i doubt this is the answer because i don't have all the information but if trouble was brewing in a clinic maybe it was an argument as to which clinic was better or smth of that nature