For a rainy day, three melancholic songs with horses.
The first, I believe (as "Officers" was) to have been inspired by the experiences of the Afghan War:
Есаул (set to Civil War era video)
The second, I know very little about (beyond the "horse" of the title) other than that it is sung beautifully:
конь
Finally, an old cossack song, in which a trooper first has a nightmare and then his captain (his Есаул) explains it probably means they're all going to die...
Ой, то не вечер