Fantasy books, where boy somehow turned into a girl

All i rememeber is the fact that teenage guy got turned into a woman. He did not do it by himself, someone (i think it was his mother) did it, because she wanted to save him from some kind of danger. Plus, i'm not sure od that, but i think there was a war going on in this world. I know that's not much, but maybe someone's got an idea?

Sounds like the Arthurian story of Percival - maybe a modern retelling? Here Lies Arthur by Philip Reeve is a possibility.

Do you have a date range to narrow it down? Off the top of my head though this reminds me a lot of Lynn Flewelling's The Bone Doll's Twin which is the first in a trilogy. The actual transformation back to a woman doesn't happen until the third book The Oracle's Queen.

Sadly, neither od those books are the one i'm looking for. I remember i was reading it about 6/7 years ago, so it can not be written past 2011 let's say, although i think its a bit older than that. One more thing that i recall : after the transformation into a girl, main character was living in some kind of dormitory, or school/academy along with other girls. I'm still trying to force myself to get more details outside my head though. ( Btw, english is not my native language, sorry if some of my sentences look terribly bad, doing my best here)

Do you remember the rough time period of the setting? I know you say it's fantasy, but was it modern-ish, medieval-ish, ancient? And was the character really transformed into a woman or just in disguise? (I'm reminded of the part of the Achilles story where he's living disguised as a woman, because his mother sent him there rather than allow him to fight at Troy, and am wondering if this story is riffing on that.)

Yes, He was deifinitely transformed into a woman fully, i remember him to be surprised by the lack od his male genitals :P I'm not sure about that, but i think it was more of a high fantasy. It was deifinitely not ancient or medieval type of a book, possibly a modern type

Ok, I've found it, it's called The Ring of Five Dragons, by Eric Van Lustbader.

touchstone: The Ring of Five Dragons by Eric Van Lustbader