117 years ago today, John Holland sold the 64-ton submersible Holland VI to the Navy, marking the beginning of our submarine force. Several months later, the submarine was commissioned as USS Holland (SS 1).

Here’s a look at how submarines have continuously adapted in both quantity and quality to address more complex and rapidly evolving challenges.

Then...

1.         The world’s first submarine used in warfare, the 8-foot-long Turtle, debuted during the American Revolution. With an oak made, walnut-shell-shaped casing, it bobbed just below the water’s surface. The one-person craft was paddled using a hand crank. It’s objective was to attach an explosive to the hull of an enemy ship and get away before the explosion. In its one combat use, it failed to successfully attach the explosive, however it gave the Royal Navy enough of a scare that they moved their ships to safer distance from American Forces.

2.         Experimentation in subsurface craft continued after the American Revolution, including a Confederate boat, Hunley, that sunk a Union warship. Still, it wasn’t until 1900 that the Navy finally commissioned a sub. Even then the technology was rudimentary but continued to improve into World War II where the submarine came of age through legendary acts of heroism and warfighting excellence. Fleet Adm. Chester Nimitz said, “We shall never forget that it was our submarines that held the lines against the enemy while our fleets replaced losses and repaired wounds.”

3.         Research and development to enhance the firepower, survivability and endurance of submarines continued after the war, culminating with perhaps the most significant technological advance in submarine history: the advent of nuclear propulsion. On Jan. 17, 1955, the crew of USS Nautilus (SSN 571) cast off lines and signaled the memorable and historic message, “Underway on Nuclear Power.”

4.         Late in 1955, Chief of Naval Operations Adm. Arleigh Burke established a special project office charged with developing a fleet ballistic missile for sea launch. Just four years later, USS George Washington (SSBN 598) was commissioned. Within six months of commissioning, the ship successfully test fired two Polaris missiles and, within six months of that, deployed for the Navy’s first strategic deterrent patrol. As of June 2014, U.S. submariners have completed more than 4,000 such patrols.

Now...

5.         Today’s Navy submarines are 100 percent nuclear powered – patrolling the depths of our oceans, taking the fight to our enemies and providing maritime security around the world.

6.         We have 69 commissioned submarines – attack (SSN), fleet ballistic missile (SSBN) and guided missile (SSGN).

7.         Our submarine force includes approximately 28,000 officers, enlisted Sailors, civilians and Reservists. In 2011, female officers began serving aboard U.S. submarines. On June 22, 2015, the Navy announced the selections of the first enlisted female submariners, marking a key milestone in the continued integration of women into the Submarine Force.

8.         Our submarines are responsible for the #1 mission within the Department of Defense – strategic deterrence – accountable for approximately 50 percent of nuclear warheads.

Future...

9.         The 12-ship Columbia class will replace the existing Ohio-class nuclear ballistic submarine force; the first patrol of the lead ship, SSBN 826, is scheduled for Fiscal Year 2031.

10.       The Columbia class reached Milestone B Jan. 4, enabling the program to move into the engineering and manufacturing development phase, where the attention is on achieving an 83 percent design maturity prior to construction starting in 2021.