CHICAGO (CBS) – It’s National Donut Day!

And you know what that mean? FREE DONUTS!

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But did you know the holiday actually started right here in Chicago?

It began in 1938 as a way to honor the Salvation Army’s “Doughnut Girls.”

Nickname “Donut Lassies,” these women served coffee and donuts to soldier in the trenches during WWI and WWII. The donuts were often fried in soldiers’ helmets.

And today (Friday) in honor of National Donut Day, donut shops are offering all kinds of sweet treats, including Glazed and Infused with a special donut created just for the holiday.

Glazed and Infused on Friday and Saturday will be serving a special Salvation Army donut. It is a vanilla bean glazed donut with sprinkles in the Salvation Army colors – red, white and black. The donut will be available at all Glazed and Infused location beginning at 7 a.m. Friday for $3 each or $30 for a dozen.

CBS: Why was it important for Glazed and Infused to get involved in the holiday realizing it is so much more than just a day to get a deal on a donut?

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“The Salvation Army contacted us and Donut Day started in Chicago in 1938, so it was really a natural partnership with us,” said Robyn Jones with Glazed and Infused. “We are Chicago’s donut so we are working with them and 50 percent of sales from this donut today and tomorrow are going back to the Salvation Army.”

Glazed and Infused locations will even have a Donut Lassies passing out the special donuts and gift cards offering one free vanilla bean glazed doughnut, valid only with any purchase, redeemable June 5 – July 5.

Other donut shops participating in National Donut Day include:

Dunkin Donuts: Guests can receive a free classic doughnut of your choice with the purchase of any beverage all day Friday while supplies last.

Krispy Kreme: Guests can receive a free doughnut of choice. No purchase necessary.

Stan’s Donuts & Coffee: Guests can receive a free donut with any purchase.

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There are many other donut shops across the city without offers, but are still serving up your favorite sweet treats.