Complex sentence: Her previous skipper had been unable to complete a war patrol for more than a year; every time he took her out, before she had been on patrol more than a few days, materiel failures would require Kapitanleutnant Peter Zschech to turn back for repairs.
Split into simpler sentences: Her previous skipper had been unable to complete a war patrol for more than a year. Every time he took her out, before she had been on patrol more than a few days, materiel failures would require Kapitanleutnant Peter Zschech to turn back for repairs.