根据factcheck.org，Walz在他部队接到去伊拉克命令的两个月前就退役参选议员了

https://www.factcheck.org/2024/08/attacks-on-walzs-military-record/

Vance claimed that Walz “dropped out” of the National Guard when he learned his battalion was slated to be deployed to Iraq. Walz retired to focus on a run for Congress two months before his unit got official word of impending deployment, though the possibility had been rumored for months.