Count Amedeo Preziosi, illustrations of the "Albanians Mercenaries in the Ottoman Army", which was Published by Lemercier & Cie, Paris, in 1857, shows that the Ottoman Army, like the Egyptian Army maintained a force of Albanian mercenaries. According ‘Khedive Ismail's Army', by John P. Dunn (2013) - The Khedive of Egypt, up till 1853 placed great value on Albanian mercenaries, and by the start of the Crimean War 4,500 Albanians were part of the Egyptian Turkish army – maintain their traditional role as skirmishers, mountain warfare experts, police and security and bodyguard units.
In Egypt, use of these troops can be dated back to 1848, organised as traditional Ottoman Bashi Bazouks, and receiving “state-of-the-art weaponry in the form of American revolvers” (which would have to be the Revolving gun made by Samuel Colt, patented first in 1848, and then 1850).
The Ottoman Albanian Mercenaries, mainly wore either green jackets edged in red tape and embroidery, or red jackets edged in yellow/gold tape and embroidery. This was combined with the fustanella (a long-skirted shirt (which later formed part of the Greek national costume).
The combination of the red jackets edged in yellow/gold tape and embroidery, and the the long white 'Fustanella', became the basis of the uniform-costume of the Turkish Imperial Army Corps of Bashi-Bazouk (1860-1877).
The origin of the Bashi-Bazouk as a military formation was mercenary soldiers, intended to act as irregular skirmishing troops of the Ottoman Empire. They were notorious for their indiscipline, plundering, and brutality.
The word 'Bashi-Bazouk (or Bashibazouk)' is Turkish literally meaning "free headed", "leaderless", "disorderly" and was a specific mercenary irregular soldier of the Ottoman imperial army, of the 1860s-1870s.
The term is often incorrectly applied by Western writers throughout the 19th century, and still currently to identify all types of Ottoman army irregulars, when it actually related to a specific band of Ottoman mercenary soldiers who operated in Gallipoli, the Ionian coast, and the Balkans, under the control of Ottoman imperial court officers.
Above/Right - These two figures have been extracted from the Vinkhuizjen Collection, from a set of uniforms of the Ottomam Imperial Court in the early 1860s. Figured among these figures in the overall commander of the Bashi-Bazouk Corps, the 'Chief of the Bashi-Bazouk', who is an imperial army colonel, and 'Aide-de-camp to the Sultan', which is indicated by the crescent badge above his cuff rank insignia (Above/Far-Right).
The Bashi-Bazouk Corps were largely organised as cavalry/infantry brigades of companies, under the command of a chief, with the rank of Bimbashi. Companies and squadrons were commanded by imperial army officers, with the rank of Yuzbashi (Captain), and Mulazim-i-evvel (Full-Lieutenant). Notwithstanding their 'irregular character' they appear to have been identified with specific type of uniform costume.
The corps likely numbered 1,000, to about 2,000 officers and soldiers. Employed as a mercenary force, given carte blanche authority to act-on-their own as an irregular force operating ahead of the Imperial Army on campaign to wreak as much havoc as possible among enemy populations and armies (which had been a traditional feature of Ottoman warfare with the use of the Akinci in the 16th century).
Right - The 'full-dress' version of the 'Chief of the Bashi-Bazouk' uniform extracted from the Vinkhuizjen Collection. This particular illustration has been dated to the 1820s, and the label attached identifying this figure as the "Nizami djedid BIMBACHI Chef de Batailion de la 1st Reform du Sultan Mahmoud", with a hand-written attribution date of "1820"  . However, this identification is likely wrong. It can be identified as part of a set made by Jean Brindesi, and published by Lemercier, Paris, 1855. This particular illustration (Right), resembles the Chief of the Bashi-Bazouk, in the Imperial Army from the 1860s till the 1870s (Above/Far-Right). This figure is an 1855 officer, in the earlier formation of the Bashi-Bazouk (from the mid, and the immediate post-Crimean War period).
Crimean War accounts mention “Beatson ... wore a gorgeous uniform blazing with gold to impress the Turks. The Bashi-Bazouks wore similar uniforms.”  It was also said by Richard Francis Burton, "I was in the gorgeous Bashi-Bazouk uniform, blazing with gold, ... he said. Beaston’s jacket was said to be so stiff with gold embroidery that it could stand up of its own accord.” 
Right - Two figures extracted from the Vinkhuizjen Collection, the description used for these two soldiers, from the 1860s period is "Zeibek", which is actually referring to the 'Efe' the leaders of Turkish irregular soldiers and guerrillas from the Aegean Region of Anatolia. These two figures are wearing uniform-costumes which have clear similarities to the officer, and the Chief of the Bashi-Bazouk, in the Imperial Army from the 1860s till the 1870s (Above/Right). They are both wearing 'Fustanella' (long skirted shirt), as well as breeches. Each figure has different zouave jacket lace details, one with a double-line boarder, and the other with a thick wavy line boarder, likely indicating different junior officer's ranks.
The Ottoman military policy of using Bashi Bazouk came to an end during the Russo-Turkish War of 1877–1878, due to their excesses forcing the Ottoman government to abandon their use .
 It also needs to be understood, that "The Vinkhuijzen Collection of Military Costume Illustration" was assembled by H. J. Vinkhuijzen (1843-1910), a Dutch physician, and presented to the New York Public Library by Mrs. Henry Draper in 1911: "Dr. Vinkhuijzen's usual strategy was to extract plates from illustrated books and magazines. He colored some of the printed images, and when printed images were lacking, drew others by hand. Some of the unsigned watercolors found in the collection may also be by him. He arranged his collection as loose images in boxes according to his own classification system; this organization is retained for browsing the digital collection. (Mounting the plates in scrapbooks was apparently accomplished by others after Dr. Vinkhuijzen's death.)"
 The figure is included in a set of Jean Brindesi plates picturing the “Anciens Costumes Turcs de Constantinople, 1855”. Whereas the rest of the Jean Brindesi illustrations of the late-period Janissary, and Sultan's Palace military appear reasonably consistent with other known soldiers from the period, it does not look like the known post-1826 'Ottoman Army Colonel's uniform'.
Right - Painted in 1869, illustrates the flamboyant uniform-costume of the Bashi-Bazouk (1860-1870). They wore a distinctive flamboyant uniform-costume. Which incorporated the 'Fustanella' (the long skirted shirt); as well, tall dome-shaped fez, wrapped in silk scarves. The uniform-costume of the Corps of Bashi-Bazouk (1860-1877), also used red (with yellow/gold facings) 'Greek -short jackets' for officers, and red Zouave jackets for soldiers.
Over the basic uniform was layered elaborate scarves in the field, or on patrol, so that the Bashi-Bazouk could present an intimidating image to shock or scare their opponents.
The uniforms rank system was based on the 1861 pattern of cuff chevrons. Commanded by a Chief of the Bashi-Bazouk, in the Imperial Court (see discussion above), the remainder of the corps had a simplified rank system, consisting of the following officers:
The Bashi-Bazouk generally carried a green flag, on a red pole with a silver spear point. This detail can be seen in the Horace Vernet (1789 - 1863), painting 'A Bashi-Bazouk', based on a figure seen in the Crimean War.
Right - Barracks of the Bashi-Bazouks at the Chibouk Chular Khan, Adrianople (From 'The Illustrated London News'). In barracks, the Corps of Bashi-Bazouk wore simple plain uniforms, with fez. It was only in the field, or on patrol that the Bashi-Bazouk 'dressed-up', in their tall hats etc in order to shock their opponents.
Right - The mounted contingent of Bashi-Bazouk. showing their elaborate costumes. Extracted from "Les Bachi-Bouzouks". Printed on border: "Il est interdit de vendre séparément cette reproduction." "Copyright 1897 by Jean Boussod, Manzi, Joyant & Co." "Souvenirs de Crimée, page 130 ... July 1897." The horse furniture, used by the mounted contingent of Bashi-Bazouk company, were elaborate 'medieval-fantasy' kits, with red cord horse aprons, intending to shock opponents.