Put Down Your Sword, Darling!

She allied herself with hostile power for her own country, but ended up killed by her brother after suffering from years of humiliation. When she wakes up, she finds herself back to her young age with the only ambition to avenge herself on those who turn their back on her, especially her royal brother. To her surprise, she's not that cold-blooded to murder the young brother before her...

(Source: WebComics)