A raglan sleeve is a type of sleeve whose distinguishing characteristic is to extend in one piece fully to the collar. It is popular in sports and exercise wear and it has been adapted to numerous other garments.
It was named after the Lord Raglan British commander during the Crimean war , probably because it was designed to fit his coat for the arm lost in the Battle of Waterloo.
Crimean War 1854-56
Death toll 300,000. 
2. The Encyclopedia of Fashion. From 1840 to the 1980s. Georgina Ohara 1986. p.67
In these designs shirts with raglan sleeves are transformed to promote human rights: