karl

this must be Archduke Karl Franz (the title typed has a C instead of the K in the photo) He would be the last emperor of Austria (Charles I) (and future saint) Likely photographed here as Franz Ferdinand has been assassinated about 6 weeks earlier and he was now the heir, and war was on, Austria had declared war on Serbia 10 days before this shot, it is likely a mobilization event. en.wikipedia.org/wiki/Charles_I_of_Austria

Charles Neufeld was an Austrian merchant who spent twelve years as a prisoner in the Sudan, starting in 1887. He published a memoir, A Prisoner of the Khaleefa: Twelve Years' Captivity at Omduran, in 1899.
query.nytimes.com/gst/abstract.html?res=F50812FE39541B728...
archive.org/details/prisonerofkhalee00neufuoft

Another book, Under the Rebel's Reign: A Story of Egyptian Revolt, followed in 1900:
www.gutenberg.org/files/23829/23829-h/23829-h.htm

He was born Karl Neufeld and is found frequently under that name as well. A pretty colorful character.
An 1898 account of his life through his imprisonment:
query.nytimes.com/mem/archive-free/pdf?res=F70717F83A5D11...
Here's an 1899 account of his life after he was freed from prison and went to London.
query.nytimes.com/gst/abstract.html?res=F60B11F93F5414728...
In November, 1915, he was reported arriving in Constantinople en route from Medina
query.nytimes.com/gst/abstract.html?res=F20E15F73C5A11738...
A German Wikipedia article on an unsuccessful German expedition to establish communications and propaganda centers in Yemen during 1916 mentions that he was part of the expedition.
de.wikipedia.org/wiki/Stotzingen-Mission
There is a further account of his life published in July, 1918 when he died in Germany.
query.nytimes.com/gst/abstract.html?res=F20E15F73C5A11738...
An ancestor has posted a short biographical account:
www.egyptedantan.com/carlneufeld.htm
There really should be a Wikipedia entry for this fellow.

Correct link for the November 1915 NYT article above (about returning from Medina) is
query.nytimes.com/gst/abstract.html?res=F10911F8385B17738...

The Grey River Argus , 3 February 1916, Page 3
paperspast.natlib.govt.nz/cgi-bin/paperspast?a=d&d=GR...
suggests that he was sent to Medina as a spy and/or to spread disinformation.

An engraving of Neufeld:
www.ub.bildarchiv-dkg.uni-frankfurt.de/CD/3317/2014/0835/...
and a postcard
my.opera.com/Elsir/albums/showpic.dml?album=470676&pi...
and a postcard of Neufeld and his monkey in Aswan, Egypt:
www.chinons.fr/Client/Module/galerie/galerie/7/7428.jpg

Thanks pennylrichardsca, artolog and swanq. The links are great. This guy seems like quite a character. I'll ask that we add Charles and Karl to the record.