Coast Guard checks went undelivered Tuesday because of the partial government shutdown — the first time ever a U.S. military service is working without pay, Military.com reported.

Adm. Karl Schultz tweeted Coast Guard service members would not get their regularly scheduled mid-month paycheck, urging them in a letter to "stay the course, stand the watch, and serve with pride. You are not, and will not, be forgotten."

"To the best of my knowledge, this marks the first time in our nation's history that servicemembers in a U.S. Armed Force have not been paid during a lapse in government appropriations," Schultz wrote.

The Coast Guard, the only military service to fall under the Department of Homeland Security, got a one-time emergency payment to issue final paychecks for 2018, but will not be able to distribute further pay until a budget deal is reached — or another appropriation agreement is made, Military.com reported.

In all, some 55,000 Coast Guard active-duty, reserve and civilian members are going without pay; the number includes 42,000 active-duty service members, Military.com reported.

"Your senior leadership, including [DHS] Secretary [Kirstjen] Nielsen, remains fully engaged and we will maintain a steady flow of communications to keep you updated on developments," Schultz said in the letter.

"I recognize the anxiety and uncertainty this situation places on you and your family, and we are working closely with service organizations on your behalf."

The organizations include the Coast Guard Mutual Assistance, the service's official military relief society, which got a $15 million donation from USAA to support those in need.

"I am grateful for the outpouring of support across the country, particularly in local communities, for our men and women," Schultz wrote. "It is a direct reflection of the American public's sentiment towards their United States Coast Guard; they recognize the sacrifice that you and your family make in service to your country."