It's fair to say that Prit Buttar is one of the world's leading experts when it comes to conflict in Eastern Europe in the early part of the 20th century. So it is no surprise that the BBC went to him for a list of pertinent facts about the Eastern Front in World War I.
The History Extra article is entitled 'Ten things you (probably) didn't know about the bloody eastern front in 1914' and it begins with a point about the monstrous casualties in the Eastern theatre:
"Casualties on the eastern front were every bit as heavy as on the western front
The Russian 2nd Army was destroyed before the end of the first month [August] at Tannenberg, with more than 100,000 men killed, wounded or taken prisoner. By the end of the year, the Austro-Hungarian forces had lost more than 1.2m men. No nation was prepared for casualties on this scale, resulting in huge numbers of wounded men being left days or weeks without any medical care."
The full article is available here. It's a great read and articulates the reasons that the Eastern Front was as important and as tragic as the monumental fighting in the West