Complex sentence: On 24 April 1945 "U- 546" made contact with a destroyer escort and was proceeding to attack firing a stern torpedo when the destroyer turned into it while diving which tore the DE apart and sent her down with heavy loss of life.
Split into simpler sentences: On 24 April 1945 "U- 546" made contact with the destroyer escort and proceeded to attack, firing a stern torpedo. The destroyer turned into it, was hit, tearing the DE apart and sending her down with heavy loss of life.