1. The coast line was crowded with u-boat nests . 2. On the second night we approached the u-boat stream . 3. The next day the u-boat was towed by a trawler to iceland . 4. The small ship came around the headland and steamed toward the u-boat . 5. The lethal power of the air in u-boat warfare was yet to come . 6. The u-boat packs were kept underwater and harried continually . 7. Hitler complained that this single invention was the ruin of the u-boat campaign . 8. One night his ship, the stork, pursued and rammed a u-boat in the darkness . 9. The problem of how to contact the u-boat on monday had been nagging at the back of his mind . 10. The work of mercy was interrupted by the appearance of u-boat and the british ships were compelled to withdraw .
