If you're talking about the Viking "long boats", the Vikings used them for raiding foreign lands. Raiding is a form of warfare.
they used boats and donkeys. Horses wer not used as much. They used long boats for long voyages.
Boats. Aircraft. Boats. Aircraft.
Trade, war, and transportation
Yes
See website: Patrol Torpedo Boats (PT Boats)
Germany used U boats.
3-masted Schooners and Viking Long Boats (or any oar powered war ships)
Tanks, U boats, Long range shelling, and Gas attacks
1,154 were commissioned.
To sink ships.
Germans
Germany