Intended for those in military service, this resignation letter is respectful and polite.
Dear Mr./Ms. Bossname
I am sorry to notify you of my impending resignation from (company), effective (date).
Although I have enjoyed my work here and gained wonderful experience from this company, I feel that I have a duty to my country as well. With that in mind, I have enlisted in the armed services in the (branch) branch. I will be reporting for training in (location) on (date) and will therefore be relocating.
Thank you for everything you've done for me. Thank you as well for your understanding as I transition to this important period in my service career.