"The standard attack pattern for Sub-Pod squadrons is best summarized as Dive - Attack - Withdraw - Coffee Break. Deviate from this pattern only in the most extreme circumstances."
M1A1 Piranha Sub-Pod Instruction Manual
The Grypho-Dolphin War in its earliest month was a relative bloodbath for the Griffins. Griffin and Minotaur Infantry, armed only with SCUBA gear and harpoon launchers simply weren't fit to deal with underwater combat. Combined with the savage manner in which Dolphins engaged in melee resulted in a lot of defeats and lot of limbs washing back onto the shore even to this day. After the second Battle of the Gallian Reef, top brass of the Gryphonian Military decided to throw what money they had at some engineers and scientists to devise a way to combat the Dolphins and minimize losses.
One of the earliest faults of the Griffins was that they lacked effective artillery support underwater, they simply couldn't point guns and cannons into the water and fire. Depth charges were used for some time, but their slow-to-deploy nature combined with them exploding at the wrong time in the best cases meant they needed to be phased out. Fortunately for the Griffins, a unicorn engineer devised a concept for a "Submersible fighter" that could bring explosives to bear against Dolphins while at the same time be able to screen infantry formations underwater.
The result of this concept was the M1A1 Piranha Sub-Pod. The Piranha (named for a ferocious meat-eating fish) is a bullet shaped submersible capable of carrying a pilot and a co-pilot (In the earlier stages, only griffins.) The engine allowed the Piranha a maximum speed of 30 knots and the unique four finned design gave it surprisingly agility and maneuverability. The two side fins are specially designed to be able to carry a standard payload of eight miniature torpedoes (dubbed Teeny Torries by the troops) that, when fired properly, can explode with such force as to take down entire swarms of Dolphins in a single run.
A more revolutionary concept appeared within the Piranha, a battery separate from the engine allowed the Piranha to maintain lights and radio contact without having to drain the engine of its own power. This allowed the Piranha numerous amounts of room to work with operating alone or in the standard squadrons of fifteen. The Piranha's air supply can last over an hour of continuous use, allowing Piranha squadrons to move with infantry underwater for long periods, and even longer periods when supported by a mothership.
The M1A1 Piranha Sub-Pod was the first variant to be deployed during the war, and its first deployment during the fourth Battle of the Gallian Reef turned the tide of the battle in the Gryphons favor. The Dolphins could not keep up with the Piranha's speed and their close combat oriented forces were slaughtered by the Piranha's torpedoes. A single Piranha scored over eighty-seven confirmed kills before victory was declared. The Piranha had exceeded expectations, and the top brass mandated that Piranha Sub-Pod be used to its fullest potential as a main battle vehicle for infantry rather than support.
By war's end, Sub-Pod squadrons outnumbered infantry formations in most skirmishes, if there were infantry formations even present.
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As the Sub-Pod was receiving praise for its role in turning the fourth Battle of the Gallian Reef into a victory, engineers were still looking for ways to bring support to the infantry underwater. A request by top brass especially was being worked on, that a "cruiser which can safely transport troops to the sea and act as a forward base" was possibly the most specific they asked. Most believe that a submersible of that size was relatively impossible, however the famed Griffin engineer and scientists Archimedes Firearm devised a workable concept by, as he says, "making it bigger."
The Nautilus-Class Submersible Cruiser was the result of over three months of tired work for Archimedes and his crack team of engineers. Technically, it is a true submarine by the fact that the Nautilus can literally operate underwater indefinitely. Archimedes devised a way to allow the crew to recycle oxygen using electricity and water, and scrub CO2 at the same time, though he never elaborates just how exactly this works (At least a few people theorize that he doesn't actually know how it works). The first prototype was over 380 Hooves in length, as large as an actual Gryphonian Battlecruiser. On the extreme front was the bridge, which was encased in a glass observatory, allowing the commanders a full view of the area. The armament was four turrets armed with two torpedo launchers, allowing a full payload dispersal of eight torpedoes. The two propellers in back were powered by twin engines that could allow the sub a speed of eighteen knots. Another feature was the ability for the sub to deploy a squadron of Sub-Pods from the bottom.
The Military produced at least one fully working Nautilus dubbed the Drebbel during the war. The Drebbel performed with admirable action in the Seventh Battle of the Gallian Reef. The Nautilus Submarines however entered the war late enough that the Drebbel was the only one of its class that saw actual combat. However, the hierarchy within the Gryphonian kingdom recognized the potential for the Nautilus-class as an explorer Submarine and donated generous amounts of money for more to be produced. Today, there are over six Nautilus' in service, the Drebbel, the Hunley, the Alligator, the Spearfish, the Nemo and the Pytheas. Other nations such as the Principality of Equestria are currently attempting to purchase one of their own.