Three White Soldiers is a bullish reversal pattern consisting of three reasonably long white real bodies.
The pattern is the inverse of Three Black Crows.
Each session opens inside of the real body of the prior candle and then proceeds to trade higher.
Each session should close at or close to the high of the candle.
The nature of the bullish move is evidenced by some selling pressure which is overcome by the end of the day by the bulls and creates more of a balanced and sustainable up move.