轻扣城壁碧血染就桃花
[qīng kòu chéng bì bì xuè răn jiù táo huā]
This is more of a poetic statement. 'Gently knocking on city walls, green blood paints peaches red'. 'Green blood painting peach blossoms red' evokes imagery associated with heroic sacrifice in war, where even tragic scenes can have some form of beauty and romance involved.