Complex sentence: In one of their last experiments, they tie a number of Chinese prisoners to crosses, intending for them to be used as targets for a prototype ceramic bomb containing infectious fleas; however, they are not able to contact their airfield due to a retreat.
Split into simpler sentences: In one of their last experiments, they tie a number of Chinese prisoners to crosses, intending for them to be used as targets for a prototype ceramic bomb containing infectious fleas. However, they are not able to contact their airfield due to a retreat.