If you like the idea of Strike Witches but find it too silly, then "The Saga of Tanya the Evil" might be for you. It has flying witches (male and female) wearing clothes appropriate to the period and weather. Trench warfare is bloody and horrible, but it's interesting how the mages from each country have different styles (the "French" ride mechanical horses, while the "Swedes" ride flying skis).

The series is on Crunchyroll, and I will agree with drakensis that Tanya is a horrible, horrible person. The only thing that really makes it watchable is that Karma is a Bitch. No matter how she plots and plans, things will never go completely her way because she literally pissed off God.

I don't think she's a good fit for OWaW, though, as she's just too nasty to fit the tone. Now her Sancho Panza, Viktoriya Ivanovna Serebryakov, would fit, but by 1946 she would be either ruling the universe from beyond the grave or checked into a psycho ward for extreme PTSD.