i rarely cut & paste from SWJ responses, but the comment by 'RantCorp' has three "gems" from historical, Western experiences. First and I admit this didn't feature in my looking back at history:
The Indian Mutiny of 1857 being the mother of all green on blue attacks in this neighborhood. However what is often overlooked is that the Mutiny was mercilessly put down by forces which were comprised 80% native troops.
In Vietnam 'blue on blue':
In VN after records started being kept from 1969 the incidence of ‘fragging’ ran up to 500 a year with 10% being fatal. This record was only concerned with attacks using fragmentation grenades. One can only speculate how many ‘wild’ bursts or ‘negligent’ discharges which resulted in fratricide were done with varying degrees of malice.
In WW2 with US paratroopers 'blue on blue':
What surprised him on D-Day and still startled him 40 years later as he recounted the events was some individuals didn't even hit the ground before they were shot dead by their comrades.
Link:http://smallwarsjournal.com/jrnl/art/vsoalp