Complex sentence: There they were able to reclaim the mortars that had earlier been abandoned and destroyed them so that they could not be used against the Australians again, but the jeeps carrying the wounded ran into a Japanese ambush in which five Australians were killed.
Split into simpler sentences: There they were able to reclaim the mortars that had earlier been abandoned and destroyed them so that they could not be used against the Australians again. The jeeps carrying the wounded, however, ran into a Japanese ambush in which five Australians were killed.