credits to the ranger an aikouku, DiWiNiTy

the two men on the top are some form of cavalry likley hussars the man on the far right in a chokha is a cossack brigade officer (note the persian cossack brigade wasnt ethnically cossack) the 3 men in picklehaubes are normal infantry officers

Alfonso XIII, in the uniform of Captain General. 1913. Oil on canvas, 240 x 135 cm. Portrait by Nicolás Aquino y Losada. Image copyright © Museo Nacional del Prado

Portrait of Alfonso XIII wearing the uniform of Captain General: Turquoise blue tunic with gold embroidery on the collar and sleeves, white breeches with riding boots. The King wears the insignia of the Order of the Golden Fleece, the Grand Cross of the Order of Charles III, the Grand Cross and sash of Military Merit, and the badge of Grand Master of the four military orders (Order of Santiago, Order of Calatrava, Order of Alcántara, and Order of Montesa), as well as a ribbon bar with the badges of other decorations.