Welcome in, everyone. It is really great to have
you with us today. Absolutely. Thrilled to be
here. Whether you are prepping for a strategic
meeting, maybe catching up on some military history,
or you just want to understand the underlying
mechanics of how the modern world was shaped,
you are in the exact right place. That's right.
Today, we're pulling from a really comprehensive
Wikipedia article. It covers the history, the
governing rules, and the major global instances
of unrestricted submarine warfare. A heavy topic.
But a vital one. Very. And our mission for this
deep dive is to understand how a single naval
tactic did far more than just change the way
ships engaged at sea. Yeah, it went way beyond
that. Exactly. It literally rewrote global alliances.
It factored international law and it pulled entirely
new superpower nations into world wars. We are
looking at a profound historical example of technology
moving much, much faster than the law could keep
up. That is the crucial lens to view this through.
I mean, this isn't merely a chronicle of maritime
history or, you know, ships sinking in the dark.
It is a story about the fundamental tension between
emerging disruptive technology and the outdated
legacy rules of war. The old paradigm. Exactly.
When a new weapon arrives that completely shatters
that old paradigm, we usually see a period of
intense diplomatic denial. And that is inevitably
followed by catastrophic global consequences.
Okay, let's unpack this by looking at the baseline.
Before submarines completely altered the naval
landscape, maritime warfare operated under a
very specific set of customary laws. The old
rules of the sea. Right. The 1899 Hague Convention
formally codified a lot of these limitations,
but the framework itself had actually existed
for centuries. It was a system built around cruiser
rules, or as they were often called in legal
frameworks, prize rules. Right. The core concept
was actually pretty straightforward. Enemy warships,
always fair game, but civilian and neutral merchant
ships were protected by these incredibly strict
protocols. Yeah, under those traditional customary
laws, a warship commander couldn't simply just
open fire on a merchant vessel. That was a huge
violation. So what did they have to do? They
were legally obligated to execute what are known
as visit and search protocols. It is essentially
a maritime traffic stop. Exactly like a traffic
stop. but carrying massive legal weight. If a
cruiser intercepted a civilian or a neutral ship,
they could only interfere with its voyage if
it was carrying contraband. And that required
actually distinguishing between types of cargo.
Right. You had absolute contraband like munitions,
weapons, that sort of thing. And then conditional
contraband like food or fuel. But even if they
found something, even if the boarding party found
prohibited cargo from a publicly announced list,
they still couldn't just sink the ship with the
crew aboard. Customary maritime law dictated
that the attacking ship had to ensure the safe
evacuation of the merchant crew before destroying
the vessel, which makes sense on paper. But reading
through the sources, this entire legal framework
relied on a very specific power dynamic. Totally.
It was designed entirely for surface ships. Right.
A large, heavily armed cruiser. could effortlessly
pull alongside a completely defenseless merchant
ship, fire a warning shot across the bow, and
basically dictate terms. The overwhelming asymmetry
in firepower made that whole visit and search
protocol possible. But the arrival of the submarine...
completely inverted that tactical dynamic. Completely
inverted it. And the irony here is that early
submarines were actually incredibly fragile machines.
I think we often picture modern, you know, nuclear
powered Leviathans operating deep underwater
for months. Oh, yeah, not even close. Right.
The early 20th century submarine was essentially
a highly vulnerable torpedo boat that possessed
a temporary ability to submerge. Their battery
life was incredibly limited. Their underwater
speed was painfully slow and critically their
hulls were completely unarmored. So they were
sitting ducks on the surface. Exactly. If an
early submarine surfaced to conduct a visit and
search protocol, a single well -placed shot from
a deck gun, even a small one, even a small caliber
weapon mounted on a merchant ship could easily
pierce the pressure hull and send that submarine
straight to the bottom. So how did those severe
physical limitations force naval commanders to
reconsider these polite rules of engagement?
Well, it basically made the traditional rules
a death sentence for the submarine crew. For
a submarine, its only true tactical advantage
is stealth. Launching a torpedo while submerged
without offering any prior warning was infinitely
safer. But doing so meant completely discarding
the cruiser rules. Right, because a sudden submerged
strike completely removes any opportunity for
the target to be searched, to surrender, or for
that civilian crew to safely evacuate. That tactical
reality brings us directly to the Imperial German
Navy at the outbreak of World War I. Yes, a very
tense situation. They possess this new technology,
but they face intense internal pressure. The
German army is bogged down in this massive continental
struggle and high level officials in the Navy
are facing severe public and political criticism
for just sitting there. For their relative inactivity,
yeah. They desperately needed to demonstrate
their strategic value. And that institutional
desperation is the absolute perfect catalyst
for radical military solutions. Which explains
the entrance of two key figures, Admiral Tirpitz
and Admiral von Pol. Right. Buoyed by a handful
of early tactical successes, they approached
the German high command with a pretty radical
proposal. They advocated for giving U -boats
a totally free hand to attack shipping without
restricting A massive escalation. And they boldly
promised that this unrestricted tactic would
create a shock effect so profound that it could
force Britain into a conciliatory mood in as
few as six weeks. Which was an astonishingly
audacious claim. Especially when you look at
the numbers. Exactly, particularly when analyzing
the actual naval order of battle at the time.
Admiral Tirpitz was aggressively pitching these
submarines as miracle weapons, to both the military
leadership and the public in press interviews.
But in reality? In reality, the Imperial German
Navy had an extremely limited number of U -boats
actually available for operational deployment.
It was a massive strategic bluff. They were banking
entirely on the psychological terror of the weapon.
They theorized that the sheer unpredictability
of ships being destroyed without any warning
would paralyze maritime trade. Merchant captains
would just refuse to sail out of pure fear. Right.
And as for the diplomatic fallout with neutral
countries, which is a huge risk, the German Naval
Command calculated that neutral nations would
ultimately accept the submarine campaign as a
proportional and reasonable reprisal for the
devastating naval blockade that the British had
already imposed on Germany. This is a very calculated
rationalization. And it worked internally. Convinced
by this logic, Chancellor Befman Hallweg formally
approved the strategy on February 1st, 1915.
And the execution of that 19... campaign serves
as a fascinating case study in how the fog of
war intentionally blurs the lines of international
law. Because the sources reveal that this initial
campaign wasn't technically fully unrestricted,
was it? Not on paper, no. The official diplomatic
stance communicated to the world was that neutral
shipping was not to be targeted. Officially,
the crosshairs were only on Allied vessels. Furthermore,
a lot of the veteran German submarine commanders,
these were career naval officers, deeply steeped
in the maritime traditions of the cruiser rules.
They voluntarily chose to continue operating
under the old protocols. Really? Yeah, they took
on those massive tactical risks surfacing their
vulnerable boats just to give warnings and allow
crews to evacuate. But the internal directives
from the German Admiralty told a completely different
story. Oh, absolutely. Secretly, the Admiralty
was heavily encouraging its U -boat commanders
to attack while submerged and to actively minimize
their efforts at target identification. And the
underlying logic there was brutal. They figured
that the accidental sinking of neutral ships
would serve as a highly effective psychological
deterrent. Essentially frightening neutral fleets
away from European waters entirely. It was a
deeply cynical operational strategy, basically
leveraging civilian collateral damage as a primary
weapon of war. And while the campaign fundamentally
failed to disrupt Britain's maritime logistics
network to the degree Admiral Tirpitz had promised,
the human cost was just severe. Devastating.
That human cost reached a massive global flashpoint
on May 7, 1915. A German U -boat, the U -20,
deliberately fired a torpedo into the British
canard luxury liner, the RMS Lusitania. A horrific
event. It sank in a matter of minutes, resulting
in the deaths of nearly 1 ,200 people, including
over 100 American passengers. What's fascinating
here is the sheer velocity of the geopolitical
backlash. It was instant. The German high command
fundamentally miscalculated how an emerging neutral
superpower would react to the sudden violent
deaths of its citizens on the open ocean. Right.
The diplomatic outrage radiating from the United
States was immediate and explosive. The pressure
forced German Chancellor Bethmann Hallweg to
directly intervene, actually going against the
wishes of his own naval commanders? He had to
do something to stop the bleeding, diplomatically
speaking. Exactly. He secured a secret directive
that explicitly prohibited U -boats from targeting
passenger vessels and then following another
severe diplomatic crisis sparked by the sinking
of the British liner Arabic in August 1915. Germany
was forced to formally and publicly suspend the
unrestricted submarine campaign entirely. Right.
By 1916, the U -boat fleet was officially ordered
to operate strictly under the traditional prize
rules again. And a look at the operational data
from the time shows that the vast majority of
submarine attacks in 1916 were indeed conducted
on the surface. So the diplomatic guardrails
seem to have held. For a moment, yes. However,
the sheer lethality and tactical advantage of
the submerged attack remain this overwhelming
temptation. Especially as the war of attrition
on the Western Front just continued to grind
down the German state. Exactly. Here's where
it gets really interesting. In early 1917, Admiral
Henning von Holtzendorf, the chief of the Imperial
Admiralty staff, presented a new memorandum to
the German High Command. And this was a game
changer. He argued aggressively for the reinstatement
of unrestricted submarine warfare, but on a dramatically
larger scale than that 1915 campaign. He presented
this as the singular definitive method to inflict
tonnage starvation on the British Empire and
force a surrender. We are looking at one of the
most consequential, heavily calculated risks
in the entire history of military strategy. No
exaggeration. The German High Command understood
clearly that authorizing this campaign meant
crossing a definitive red line. They knew with
near absolute certainty that resuming unrestricted
attacks would trigger a declaration of war from
the United States. So knowing the massive industrial
capacity of the U .S., how did the German Admiralty
possibly justify taking that mathematical gamble?
They relied on a very strict logistical timeline.
Holtendorf's memorandum argued that a massive
unrestricted U -boat offensive would sink enough
British shipping tonnage to force a complete
collapse of the UK economy within five to six
months. Very tight window. Very tight. They calculated
that the United States military mobilization,
training, and transatlantic deployment would
simply be too slow. So it was a race. Exactly.
The gamble was that Germany could strangle Britain
and secure victory on the continent before American
expeditionary forces could arrive in sufficient
numbers to actually alter the balance of power.
The decision was made. Germany unleashed the
U -boats. And just as they predicted, it served
as a massive trigger mechanism. It absolutely
did. When combined with the public exposure of
the Zimmerman Telegram, where Germany actively
proposed a military alliance with Mexico against
the U .S., the resumption of unrestricted submarine
warfare officially ended American neutrality.
The United States entered World War One. I want
you to consider the immense historical weight
of this strategic gamble, a singular tactical
decision regarding the deployment parameters
of a specific maritime vessel made by naval planners
in a war room. effectively sealed the trajectory
of the entire global conflict. Incredible. It
pulled a rising industrial superpower right into
the European theater and permanently altered
the geopolitical landscape of the 20th century.
And the bitter irony for the German Admiralty
was that their timeline completely failed. Right.
The Yubo campaign caused immense destruction,
no doubt about it, but it did not break the British
logistics network in time. And the American forces
did arrive. They certainly did. So World War
I eventually concludes, leaving behind unprecedented
devastation. And in the aftermath, the international
community was deeply, deeply traumatized by the
memory of the Lusitania and just the sheer ruthlessness
of the U -boat campaigns. The psychological scar
was massive. Right. There was a massive diplomatic
push to ensure submarines could never again be
used as weapons of commerce reading. And this
led directly to the 1922 Washington Treaty on
poison gas and submarines. And the objective
of that treaty was crystal clear to impose such
severe operational restrictions on submarines
that they would be rendered strategically useless
against merchant shipping. It was signed by major
naval powers, including the United States, the
United Kingdom, Japan, France and Italy. But
the fatal flaw of the Washington Treaty was a
procedural one? Yes, it required unanimous ratification
to enter into international law. And France,
looking at its own maritime defense strategy,
viewed the submarine as the ultimate asymmetric
weapon. A poor man's navy. Exactly. A way to
defend its coastlines against the much larger
surface flutes of its rivals. So France refused
to ratify the treaty, rendering the sweeping
prohibitions entirely dead on arrival. The international
community attempted to close the gap again later
with the 1936 London Protocol on submarine warfare.
Right. Trying again. This agreement was much
more specific. It mandated that submarines strictly
adhere to the traditional prize rules. If a submarine
intended to sink a merchant vessel, it was legally
required to surface, conduct a visit and search,
and critically, place the civilian crew in a
place of safety before destroying the ship. But
the sources highlight just how quickly that legal
framework began to crumble when confronted with
the actual realities of naval technology. If
we connect this to the bigger picture of international
law, we see a persistent vulnerability, and that
is ambiguity. Ambiguity in the text. Right. Legal
scholars frequently note that nations will intentionally
engineer loopholes or tolerate vague language
and treaties to protect their own future's strategic
flexibility. Especially concerning dual use technology.
Exactly. And that ambiguity became glaringly
obvious when trying to define what actually constituted
a merchant ship. Yes. Because remembering the
devastating impact of the U -boats in WWI, Britain
adopted a policy of heavily arming its civilian
merchant vessels with defensive deck guns. Which
creates an immediate paradox in the laws of war.
Yeah. the line between a protected non -combatant
and an active combatant completely blurs. Right.
If a submarine commander surfaces to legally
execute a visit and search protocol, and the
supposedly protected merchant vessel immediately
opens fire with a naval gun, which they did,
the legal protections become a fatal liability
for the submarine. The complexities compound
even more when we look at that place of safety
requirement. Let's just pause and consider the
practical, physical reality of that rule. It's
almost absurd. A standard World War II era submarine
barely had enough internal volume for its own
crew, its torpedoes, and its provisions. Taking
on dozens of captured civilian sailors from a
sunken freighter was physically impossible. Because
taking prisoners aboard was impossible, the legal
alternative was to force the merchant crews into
their own emergency lifeboats before sinking
the ship. But think about what that means. We
really must reflect on the grim reality of this
legal fiction. forcing a civilian crew into wooden
rowboats in the middle of the North Atlantic
in January, hundreds of miles from the nearest
coastline. That is not providing a place of safety.
No, it is a delayed death sentence disguised
as legal compliance. The entire framework was
an illusion. An illusion that shattered entirely
with the outbreak of World War II. Prior to the
conflict, an incredible 48 states had signed
on to the prohibitions against unrestricted submarine
warfare, including all the major global powers.
Yet the very moment national survival was truly
on the line, those treaty obligations were rapidly
and systematically abandoned by every single
belligerent nation. The source outlines four
major historical campaigns of unrestricted submarine
warfare. The first was the WWI campaign we just
discussed. The second was the Battle of the Atlantic,
stretching from 1939 to 1945. Germany discarded
the international rules immediately upon the
outbreak of war, officially issuing War Order
No. 154, which explicitly authorized unrestricted
attacks. And the tactical evolution in the Atlantic
was profound, with submarines operating in coordinated
groups to hunt down maritime logistics networks.
The wolf packs. Exactly. Then the third major
campaign occurred in the Baltic Sea, primarily
from 1942 onwards. This was waged between Nazi
Germany and the Soviet Union on the Eastern Front,
utilizing the exact same unrestricted doctrines.
And the fourth campaign took place in the Pacific
Theater, waged primarily by the United States
Navy against the Japanese Empire. Yes. And it
is crucial to highlight the historical irony
here. The United States, the nation that had
entered World War One largely out of moral and
political outrage over unrestricted submarine
warfare, abandoned the restrictions from the
very first hours of the Pacific War. It was an
immediate shift. Following the attack on Pearl
Harbor, the order for unrestricted submarine
warfare against Japan was issued without hesitation.
Both the British Empire in the Atlantic and the
Japanese Empire in the Pacific relied heavily
on extended, incredibly fragile maritime logistics
networks to transport raw materials and sustain
their war machines. Right. They were island nations.
Which made them uniquely vulnerable to the strategy
of tonnage starvation. And the data reveals a
truly staggering conclusion. Despite the historical
focus on German U -boats and the Battle of the
Atlantic, the most devastatingly successful campaign
of unrestricted submarine warfare in history
was executed by the United States. just lethal
efficiency. Targeting vital shipments of oil,
bauxite, and raw materials before they could
even reach Japanese factories and working in
tandem with extensive naval minefields, American
submarines methodically choked off the Japanese
home islands. The numbers are wild. By the end
of the war, they had reduced the Japanese merchant
fleet to less than a quarter of its initial tonnage.
It was a master class in asymmetric naval warfare,
utilizing the exact doctrine the nation had once
condemned. as a violation of international law.
So what does this all mean? When we trace the
arc of this history, we see a naval tactic born
out of sheer institutional desperation in WWI.
Right. It was a technological leap that broke
customary maritime law, sparked enough outrage
to pull the United States into a global conflict,
and survived decades of intense diplomatic efforts
to ban it. It survived all of it. Yet, when the
ultimate test of World War II arrived, unrestricted
submarine warfare became the standard operating
procedure for all major powers, ultimately being
perfected by the very nation that first went
to war to starve it. It is a sobering testament
to the brutal pragmatism of total war. But this
raises an important question for you to consider
long after this deep dive ends. What's that?
The cruiser rules we examined failed so spectacularly
because they were written for an era of surface
ships. They completely failed to account for
the stealth capabilities of early submarines.
The technology just outpaced the law. Exactly.
So today, as modern militaries rapidly develop
fully autonomous drones, AI -driven targeting
systems, and next generation stealth weapons,
we have to ask ourselves, are our current international
laws of war about to become just as obsolete
and just as heavily tested as the rules of the
sea were in 1915? That is a fascinating, incredibly
complex thought to leave off on. We want to thank
you for joining us today as we navigated this
impactful history. It is deep dives like this
that really remind us why analyzing the past
is the most effective way to understand the architecture
of our future. Thank you for listening and we
will catch you on the next deep dive.