Order of the Red Eagle
As the Pour-le-Mérite was only awarded on very rare occasions and the Iron Cross instituted only during major wars, the Order of the Red Eagle ("Roter Adlerorden") was more commonly awarded to Prussian (and other German) officers for colonial actions. It was awarded in several classes only the third and fourth of which were awarded to officers in the field. Crossed swords and a crown could be added to the award for distinction. A lower Red Eagle Medal could be awarded to other ranks.

When several awards of the Red Eagle were made to the same recipient in different classes, only the most senior was worn. The exception was if the more junior was distinguished by swords, a bow or a crown, in which case it could be worn alongside a more senior award (see the photo of Admiral Friedrich von Ingenohl to the right).

The example in the photograph above is a 4th Class award. One such as this was awarded to Rittmeister Richard Haegele for service while commanding the Field Bakery of the East Asian Expeditionary Corps in China. He was later awarded the decoration with swords for action in South West Africa.
Recommended External Link- The Medals of Richard Haegle at Medal Net

Crown Order
The Crown Order ("Kronenorden") was the lowest Prussian Order of chivalry. It was worn on a blue ribbon for awards during peacetime years and on a ribbon like that of the Iron Cross (black/white/black/white/black) for wartime awards. As with the Red Eagle, the third and fourth classes  were awarded to field officers and crossed swords could be added for distinction. A Crown Medal was awarded to other ranks.

The crown medal is is one of the few German awards given to African soldiers in the colonies. Examples have been seen worn by Togo Polizeitruppe NCO's (see Medals of a Togo Polizeitruppe NCO at the Gentlemen's Military Interest Club) and loyal East African Arab Sultans (see the photo of Wali Mohamed bin Salim to the right).

Warriors Merit Medal
The Prussian Warriors Merit Medal ("Preussische Kriegerverdienstmedaille") had previously been awarded to soldiers of countries allied to Prussia, and was thus often awarded to soldiers of other German states during the Wars of Unification, Colonial Campaigns and First World War and to servicemen of the Austro-Hungarian, Ottoman and Bulgarian armies during the First World War.

In 1889, Unteroffizier Chamba Wadi Hamit became the first African soldier to be decorated in German service when he was awarded the Prussian Military Honour Decoration ("Militärehrenzeichen"), second class for bravery during the Abushiri Rebellion in German East Africa. Soon after, the commander of the German forces in East Africa, Hermann von Wissmann suggested the permanent establishment of a bravery award for African soldiers in German service. In 1892 a new Imperial German (rather than only Prussian) Warriors Merit Medal was instituted as an award for bravery for the askaris of East Africa. On 25th March 1893 the award was extended to non-European troops in the Schutztruppe and Polizeitruppe of all colonies.

The new German Warriors Merit Medal was identical in appearance to the previous Prussian award. It consisted of  a circular polished steel medal with a stylised "WR" monogram surmounted by a Prussian crown on the obverse and the motto "Krieger Verdienst" within a laurel wreath on the reverse. Some surviving medal bars show the Warriors Merit Medal worn reversed with the "Krieger Verdienst" showing rather than the monogram. Some Prussian Warriors Merit Medals have been seen with the slightly different motto "Kriegs Verdienst". The ribbon was vertically striped black/white/black/white/black, similar to that worn with the Iron Cross.

The first class award differed in that the obverse bore a profile portrait of Kaiser Wilhelm II in Garde du Corps uniform, surrounded by the title "Guilelmus II Imperator" (see Medals.Org.Uk). It was also noticeably larger with a diameter of 4cm rather than 2.5cm for the second class. In 1895 a "Gold" class of the medal was instituted. Aside from being in bronze it was identical to the silver medal in both the a larger first class and the smaller second class awards.

Between 1892 and 1914, 1,491 Warriors Merit Medals were awarded to non-European troops in the Schutztruppe and Polizeitruppe. A further 2,425 of various classes were sent aboard the "Marie" blockade running ship to German East Africa in 1916 for awards to askaris during the First World War.
Recommend External Link -Gentlemen's Military Interest Club discussion on the Kriegerverdienstmedaille
Highly Recommended Reading- "Askari und Fita-Fita" by Thomas Morlang

Long Service Awards
The four German kingdoms (Prussia, Bavaria, Saxony and Württemberg) and some other states (such as Hessen) each issued their own long service awards ("Dienstauszeichnung") to their soldiers. Prussian long service awards were awarded to troops from the remaining states (such as Baden) as well as Imperial troops (such as the Schutztruppe, East Asian Occupation Brigade, Navy and Marine Infantry). It should be noted that each year of wartime, overseas or colonial service counted as two years towards long service awards.

The Prussian other ranks long service award came in three classes, third class for 9 years service, second class for 15 years service and first class for 21 years service. Each higher class award replaced the previous one, so servicemen did not usually wear more than one long service award at a time.

These long service awards were originally worn as a ribbon and clasp ("Schnalle") only, usually worn below the medal bar. The clasp bore the "FW III" monogram and was in different metals for the different classes: iron for third, white metal for second and yellow metal for first class. The ribbon was blue with coloured edging down either side: black for third, white for second and yellow for first class.

From 1913 the awards were replaced by medals worn on the upper left breast or bar. The third class was a white metal circular medal bearing the Prussian crown and the motto "Treue Dienste bei der Fahne" (roughly translated as "loyal service under the flag"). The second class was a yellow metal medal bearing the same crown and motto. The first class was a bronze or yellow metal cross with the Prussian crown in the centre. The ribbon for all classes was plain blue.

The Prussian officers long service cross was awarded for 25 years service. It consisted of a yellow metal cross with the "FW III" monogram in the centre on a blue ribbon.

There were two types of Prussian Landwehr long service awards. The first class was for officers who had served 20 years. It consisted of an iron metal cross with the "WR" monogram on a yellow metal centre hung on a blue ribbon. The Landwehr second class award was officers and other ranks for completing three months active service or taking part in a campaign. It originally consisted of a blue ribbon and an iron clasp with the "FW IV" monogram. In 1913 this was changed to a white metal circular medal with the Prussian crown and the motto "Treue Dienste Reserve Landwehr") hung on a blue ribbon. Landwehr long service awards could be worn alongside (but behind) previous regular officers or other ranks long service awards.

All Prussian long service awards had the number of years in Roman numerals on the reverse of the medal, except the Landwehr second class award which had the motto "Landwehr Dienstauszeichnung II. Klasse".
Recommended External Links- Discussion on Prussian Long Service Awards at the Gentlemen's Military Interest Club
Wikipedia pages on Dienstauszeichnung and Saxon Dienstauszeichnung

Wilhelm I Centenary Medal
The Prussian Centenary Medal ("Zentenarmedaille") was awarded to all serving officers and other ranks of the Prussian army, the German navy and the Schutztruppe as well as to veterans of the Wars of German Unification on 22nd March 1897 to celebrate what would have been Kaiser Wilhelm I's 100th birthday. As such it was commonly seen on the medal bars of long serving officers and NCOs in the colonies in the early 20th Century.

Red Cross Medal
The Prussian Red Cross Medal ("Rote Kreuz Medaille") was of course awarded for service in the Red Cross medical volunteer service ("Freiwillige Krankenpflege"). The Second and Third Class awards could be awarded with the following yellow metal clasps for overseas service:

"Südafrika 1899/1900" for the Anglo-Boer War- 30 third class awards
"Ostasien 1900/01" for the Boxer Rebellion- 2 second class and 75 third class awards
"Peking" for the defence of the Foreign Legations during the Boxer Rebellion- 5 third class awards
"Charbin 1904/05" for the Russo-Japanese War- 10 third class awards
"Südwestafrika 1904/06" for the Herero Rebellion- 5 second class and about 100 third class awards

Six medics were awarded two clasps, only one ever earned three. A single unofficial third class award for the Greco-Turkish War has also been reported reading "Türkei 1897".
Recommended External Links - Articles on the Prussian Red Cross medal at the Rev. Richard Jordan's Red Cross Medals, Wikipedia and Gentlemen's Military Interest Club

Admiral Friedrich von Ingenohl
Von Ingenohl commanded the German High Seas Fleet for the opening campaign of the First World War. The medals on his bar are worn in correct order for the Imperial Navy with all the Prussian medals before those from another state. The medals are the House Order of Hohenzollern, Order of the Red Eagle third class with crown, Order of the Red Eagle fourth class with bow, Officers Long Service Award, South West Africa Campaign Medal, China Campaign Medal, Wilhelm I Centenary Medal and lastly the Saxe-Weimar-Eisenach Order of the White Falcon. Note that as Ingennohl's fourth class Red Eagle has a bow, he may wear it alongside his third class.
Photo from WikiCommons

Wali Mohamed bin Salim
Wali Mohamed bin Salim, shown here in 1902, was the Sultan of Mikindani in East Africa. Like many local leaders he maintained his status under German rule by working for them as a colonial official. As seen here he was awarded the Prussian Crown Medal for his services.
Photo by Vincenti at the Library of Congress / Wikimedia

South West African Schutztruppe NCO
He wears the South West African Schutztruppe grey home uniform with blue collar, cuffs and piping down the front. Note the NCO lace on the collar. On his left breast he wears parade aiguillette cords and three Prussian awards- the Military Honour Award second class, the Wilhelm I Centenary Medal and below them a pre-1913 Prussian 9 year Long Service Award.
Photo © JW Collection

See-Soldat, III. Seebataillon, Tsingtao
This marine wears the black Jäger style shako with black parade plume, dark blue peacetime uniform with white piping and yellow Litzen and the dark grey/black greatcoat. On his left breast he wears the Prussian Military Honour Award First Class.
Photo © Peter Klein