Without Mario Bava’s A Bay of Blood, slasher films as we know them may not exist.

Sure, there are plenty of other precursors to which the subgenre’s lineage can be traced – Alfred Hitchcock’s Psycho is a commonly-cited starting point – but 1971’s A Bay of Blood shares several direct connections. Without Bava’s kick-start, the films could be very different. Kino Lorber, the company that released the new Blu-ray edition of the film, eloquently describes the picture as “the spurting artery from which all future slasher films would flow.”

Let’s take a step back for a moment. Mario Bava, a renowned Italian filmmaker, is credited with creating the giallo genre with 1963’s The Girl Who Knew Too Much. Giallo films combine elements of crime thrillers, mystery, horror and eroticism. It’s no secret that gialli paved the way for slashers, but Bava’s influence goes much deeper than that.

Among the several successful gialli in Bava’s arsenal is A Bay of Blood, a film known by many names. The two most common monickers are A Bay of Blood and the infinitely cool Twitch of the Death Nerve, but it has also been released in certain regions under the titles Carnage, Bloodbath and even The Last House on the Left: Part II, despite being completely unrelated and preceding Last House by a year.

Although the main plot is a bit more intricate than that of your average slasher, there is an important subplot that laid the groundwork for the so-called “body count” movies: A group of carefree teenagers have a party at a waterfront cottage in the middle of the woods, where they partake in underage drinking, premarital sex, skinny dipping and other such mischief – that is, until a ruthless killer murders them, one by one.

The story, of course, bears an uncanny resemblance to Friday the 13th (and many of its derivatives). A Bay of Blood was even advertised as featuring 13 shocking deaths, just like the original Friday the 13th trailer. While it’s debatable to say the creators of Friday the 13th were directly inspired by A Bay of Blood, those responsible for its first sequel certainly were. Friday the 13th Part 2 lifts a pair of death scenes directly from A Bay of Blood: two lovers being stabbed with a spear like a human shish kabob, which is re-created nearly shot-for-shot, and a victim being mercilessly struck in the face with a machete.

Like many of the Italian horror films of the time (and the American slashers that would follow), A Bay of Blood has no qualms with gratuitous nudity and bloodshed. But Bava took the latter to the next level; although relatively tame by today’s standards, the film’s graphic violence was scorned upon its initial release. Legend has it that Sir Christopher Lee left the theater in disgust upon viewing the film. The effects were masterfully created by Carlo Rambaldi, who would later earn Oscars for his work on E.T. and Alien.

A Bay of Blood also features several first-person shots from the killer’s point of view, a technique that would later shock audiences in the iconic opening scene of Halloween and, subsequently, became a staple of the Friday the 13th series. Although earlier works, such as The Spiral Staircase and Peeping Tom, employed similar camerawork, it remains another strong connection to the genre.

The movie begins with the murder of an unsuspecting victim to immediately grab the audience’s attention, and the killer’s identity remains unknown until the end; a staple of gialli, as well as many standalone slashers. Prior to the conclusion, viewers only receive a glimpse of the mysterious killer in the form of a glaring eye as he stalks his next victims; an aspect that could very well have influenced Bob Clark’s early slasher, Black Christmas.

Visual flair is one element missing from most slashers (Halloween being the most obvious exclusion) that is abundant in A Bay of Blood. Long before beginning his directing career, Bava established himself as one of Italy’s best cinematographers. The film’s scenic locale lends itself to being photographed, and Bava (serving as his own director of photography, due to budgetary constraints) stylishly showcases it. Even the gruesome death scenes seem elegant.

Bava’s A Bay of Blood has been called one of the most influential horror films of all time, a claim that is difficult to refute upon examining the evidence. Its impact can still be felt to this day, as we see Bava’s legacy live on in the never-ending flow of remakes and sequels to the movies he inspired.

A Bay of Blood is now available on Blu-ray from Kino Lorber. It’s the latest addition to the company’s ongoing Mario Bava Collection, which also includes such classics as Black Sunday and Black Sabbath. The film, mastered in HD from a 35mm negative, is more striking than ever. Both the English- and Italian-language versions are included, along with an audio commentary by film historian Tim Lucas and trailers. Order the Blu-ray here.