Sonar
The invention of sonar was important because it allowed for the detection of objects underwater using sound waves. This technology has been crucial for navigation, underwater mapping, and locating submarines since it can operate in the darkness of the deep ocean where visibility is limited.
The submarines in WW2 are different from now. I have done research and back then submarines were easily sunk and were ran differently ! How were they ran differently ? Back then in WW2 the submarines used, were smaller ... They were ran by Diesel engines which allowed them to high surface speed and long range, but underwater it was very difficult and the speed and range wasn't the same from out of the water.
It depends on the real question. If meant literally, then yes, women are allowed on submarines. They can visit some submarines. If the question is, "Are women allowed to serve/work on submarines?" then it depends on the country. In the Royal Navy (UK) they are not allowed to serve at present. The United States, however, is gearing up to allow some women officers to serve aboard U.S. Navy nuclear submarines.
the Chinese invention that allowed soldiers to fight on horseback was The saddle and stirrups.
six battleships
The invention of writing allowed people to communicate more broadly than had previously been done.
steel
Steam
Accurate timepieces.
The telephone is a great invention in the history of communciation. The invention of radio allowed information to be rapidly sent between continents.
Merchant Ships
Barbed wire