While the submarine had undeniably become a more sophisticated weapons system by WWI, the CSS Hunley was the first to sink an enemy vessel in time of war, and was purpose built for the mission.
As for the "cellucotton" revolutionizing feminine hygiene, that comes full circle. Originally a bandaging material, then adapted to form sanitary napkins, when I was EMS we carried them on the Ambulance to use as highly absorbent bandages, and during the Iraq war it was discovered the tampon could stifle bleeding in a wound channel as well.
Poison gas and the use of motor vehicles both really got going, and the Tank was a new development, an answer to the slaughter from well emplaced machine guns.