Complex sentence: After the first frantic months of re-supply convoy duties across the Channel, she acted as a local escort for the South-western Approaches and, at the War's end, she was ordered to Milford Haven to de-ammunition and be laid up in reserve.
Split into simpler sentences: After the first frantic months of re-supply convoy duties across the English Channel, she acted as a local escort for the South-western Approaches. When World War II ended, she was ordered to Milford Haven to de-ammunition and be laid up in reserve.