Complex sentence: Although the Americans were eager for the fight they were inexperienced and did not clear German positions as effectively as they were supposed to, and the advancing Australians were forced to fight again for the ground the Americans had just "taken".
Split into simpler sentences: Although the Americans were eager for the fight they were inexperienced and did not clear German positions as effectively as they were supposed to. This forced advancing Australians were forced to fight again for the ground the Americans had just "taken".