a secret research endeavor under the
direction of the british admiralty led
to the development of a unique weapon
that would change the course of maritime
warfare during world war ii
the result of trial and error this
anti-submarine projector turned the
tides against the nazi u-boats and
wreaked havoc in the pacific
instead of dropping depth charges on
submerged submarines and causing damage
from hydrostatic shock waves a different
approach to outperform them was
conceived early in the war
the idea was to design a device that
would fire spigot mortars ahead of a
ship and have them detonate only when
they hit a hard surface
though the original fairly mortar device
was unsuccessful a new idea sprung from
the misadventure and thus the hedgehog
was born
named for its rows of launcher spigots
which resembled the spines of the
creature when devoid of a load the
hedgehog would not only redeem the
fairly but become one of the most feared
weapons against the dreaded german
submarines
[Music]
wartime innovations
after the outbreak of world war ii the
german u-boats became a perilous threat
for the allied fleet in the atlantic
thus the british were in desperate need
of a new weapon that could balance the
scale
the top secret project was carried out
by the directorate of miscellaneous
weapons development the department of
the british admiralty
the idea was to build a weapon that
would be more lethal than conventional
depth charges
the first attempt was tested in 1941
called the fairly mortar but it resulted
in failure
however the lessons learned would
eventually give way to the hedgehog an
innovative mortar capable of launching
dozens of projectiles at a time
the multiple spigot mortar or spigot
discharger was first developed by
lieutenant colonel stuart blacker based
on early infantry trench mortars
the concept consisted of a single device
capable of launching multiple target
warheads of different sizes
as part of the primary weapon the
propelling charge worked against a rod
which was set in a base plate and then
fitted inside a tubular tail stemming
from the charger's body
initially the concept was used on the
blacker bombard 29-millimeter spigot
mortar and later the p-i-a-t anti-tank
weapon
thereafter the principle was adapted for
naval use in partnership with the head
of military intelligence research major
millis jeffers
notably jeffries brought the blacker
design for use in the army
the hedgehog could fire a salvo of 24
small bombs directly ahead of a ship
the trajectory was calculated by a
mathematical arch projection with
contact aimed within a circular or
elliptical area of about 100 feet in
diameter at 250 yards
the mounting was fixed at first but was
later replaced by a gyro stabilized base
which enabled the attacking ship to roll
and pitch more freely
each mortar projectile carried a 35
pound torpex charge measured 7.1 inches
in diameter and weighed 65 pounds
the angle of the spigot was positioned
for a discharge with a diameter of 130
feet and a head of the ship by 590 feet
while sinking the bombs then descended
at 33 feet per second which meant they
could reach an enemy separating at 200
feet in under 9 seconds
remarkably the charges would only
detonate upon contact with a hard
surface resulting in more immediate and
lethal damage to a submarine than depth
charges that relied on hydrostatic shock
waves
fitted at the bow of a ship the
impressive device increased the accuracy
of anti-submarine weapons and forced the
nazis to innovate in return
advantages
each of the hedgehogs four cradles fired
six projectiles in sequence and
staggered to land simultaneously
as a result the mounting did not receive
excessive stress which avoided the need
for deck reinforcement and allowed the
weapon to be smoothly retrofitted
whenever needed
moreover reloading took no more than
three minutes
in addition the system solved the
problem of a potential target submarine
disappearing from sonar and losing
contact when getting closer than the
technology's minimum range
the characteristics of the speed of
sound when traveling through water led
to a scenario where the echo returned
from a target was too short and
therefore a human operator couldn't
distinguish the turning signal from the
original pulse
the phenomenon dubbed the instantaneous
echo caused both sounds to merge while
the enemy submarine hid away from depth
charge range
in other words the situation created a
blind spot concealing the target
submarine from the sonar enabling it to
execute evasive maneuvers and leave the
scene undetected
thus a four mounted weapon on the hunter
ship's deck that could discharge
projectiles over the bow while the enemy
vessel was visible would give the allies
a tangible advantage in the atlantic and
pacific
however the mortar was less effective
when facing deep targets
although target depth was less important
its use on objects below 400 feet was
discouraged regardless getting one or
two direct hits was usually enough to
sink an entire submarine
lack of confidence
the hedgehog entered service in 1942
and after the new mortar was installed
in about 100 ships the submarine hits
started coming
initially its success rate was only
slightly better than that of depth
charges at about five percent
the launcher was frequently covered in
swells and spray in the heavy north
atlantic weather and incomplete patterns
would be fired because of its state as
well as firing circuit problems
this would usually be a notorious reason
for discontent among the crew
in early 1943 the royal navy employed
the hedgehog so intermittently that an
order was issued for captains to report
back on why they hadn't used the weapon
upon contact with the submarine
furthermore the lack of experience and
confidence in the hedgehog contributed
to the disappointing results
consequently improved training sessions
and talks about the correct use of the
novel weapon were implemented and soon
the hedgehog's metrics improved
considerably
by the end of the war it was concluded
that one in five murder attacks resulted
in a lethal hit
in contrast less than 1 in 80 depth
charges had the same result
the new weapon was so effective that the
creek's marine implemented an acoustic
torpedo program in 1943
the new german homing torpedoes proved
effective without using periscopes
allowing submarines to remain undetected
and avoid counter-attacks
however the hedgehog would wreak
relentless havoc in the pacific in
mid-1944 due to the skillful crew aboard
the mythical uss england
unmatched performance
uss england was a buckling class
destroyer escort named after the pearl
harbor hero and john c england
destroyer escorts were a cheaper and
smaller alternative to navy destroyers
and instead of engaging in fleet battles
they were tasked with the less exciting
task of escorting convoys of slower
merchant ships across the world's oceans
the humble england had a weight of 1400
tons and a crew of 186
in contrast to more powerful destroyers
england was armed with three 3-inch guns
rather than 5-inch ones 12 anti-aircraft
guns instead of 20 and 3 torpedoes
instead of 10
but among her anti-submarine armament
the hedgehog stood out
on may 18 1944 england and two other
destroyer escorts were directed to
intercept a japanese submarine headed
towards the solomons the following
afternoon the destroyer escort sonar
identified submarine i-16
according to captain john williamson
england's executive officer the ship
attempted four attack runs over the
japanese to deploy the hedgehog but i-16
cleverly outmaneuvered her by following
the attacker's course
however four to six hits detonated on
the fifth attempt much to the crew's
delight
the stern was lifted six inches and then
plopped heavily
williamson recalled quote we had with
cataclysmic certainty heard the last of
one japanese submarine
later that month the imperial japanese
navy implemented operation ago an
extreme approach to confront the
americans in one last decisive
engagement
to begin with seven submarines were to
block the northeast side of new guinea
an expected path for the americans
the front line of submarines would give
the japanese an early warning but more
importantly they could sink enough enemy
vessels to affect the outcome of the
upcoming battle
but unbeknownst to the japanese the
americans had cracked their codes and
deciphered their orders
consequently they sent england and her
two companions to the japanese line
smashing them one by one
on may 22nd uss george detected the
japanese ro-106 submarine cruising
inadvertently on the surface
after being illuminated by the ship's
searchlight the submarine dived but
struggled to flee
england struck her with a hedgehog run
marking at least three hits
the bubbling in the surface confirmed
the end of the enemy vessel
the following two days england destroyed
ro104 and ro116
then on the 26th a hunter-killer
anti-submarine task force reached the
small fleet
the takeover allowed the destroyer
escorts to head to manus for resupply
fortunately england contacted and sank
ro-108 while on the way
after resupplying england and her
companions steamed for the remainder of
the japanese line
then on the morning of may 30th the
destroyer hazelwood spotted ro105 and
several ships joined the hunt including
george and raby
england however was ordered to stay back
following an entire day of tracing and
unsuccessful attacks england offered to
help but as williamson remembered the
reply was quote we are not going to tell
you where we are we have a damaged sub
and we are going to sink her do not come
near us
suddenly ro105 emerged on the surface
directly between the destroyer escorts
blocking their mutual fire
out of choices division commander haines
radioed quote oh hell go ahead england
england then scored between six and ten
hedgehog hits resulting in a major
explosion that ended up with loads of
oil and debris floating on the surface
to this day uss england has the record
for most submarines sunk by a single
ship with six victims in 12 days
with help from the hedgehog out of the
seven japanese submarines originally
lined up five were destroyed foretelling
the end of the pacific war
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