Was it actually popularly claimed that the Titanic was unsinkable, or did that part of the story grow in decades after the sinking?

The Titanic was not really touted as unsinkable! Or, at least, this wasn’t the major selling point that it’s presented as today.

Immediately after the sinking, the Titanic mythos began to develop. The idea that “Nearer My God To Thee” was playing as it sank, for instance, isn’t true, but became indelibly attached to the event.

There are also aspects of the mythos that are not necessarily myths, but are part of what comes to mind when you think of the Titanic’s sinking, the narrative that everyone knows and is included in every work of fiction related to it: women and children first, or steerage passengers being locked below decks. The engineers and builders being arrogant and hubristic, calling the ship “unsinkable”, is part of this mythos.

At the beginning of the extended flashback in the film Titanic, Rose’s mother says, “So this is the ship they say is unsinkable,” as though the public discourse is abuzz on the topic.

The 1955 book A Night to Remember set the idea that everyone smugly considered it unsinkable, and publications of the following decades would popularize lines like “God himself could not sink this ship!” and the belief that it was “safer than a lifeboat”.

All of this gives the impression that ships were constantly sinking and transportation companies and potential passengers were desperate for relief – which was not the case. On the other hand, a rival view (we could call it a second-option bias) appeared in the 1980s that said nobody had ever called Titanic “unsinkable” until after it sank; fewer people heard of this, but it became the insider view for a time.

As stated in the earlier answer, the idea did come up before the sinking – around the time that Titanic and its sister ship, Olympic, were built, both ships’ unsinkability was mentioned.

There’s a 1910 promotional leaflet made by the White Star Line with pictures of both being built, which stated that “as far as it is possible to do so, these two wonderful vessels are designed to be unsinkable”. There’s also a much nicer brochure from 1911, when the ships were closer to being finished, which touted the safety features:

Each door is held in the open position by a suitable friction clutch, which can be instantly released by means of a powerful electric magnet controlled from the Captain’s bridge, so that, in the event of an accident, or at any time when it may be considered advisable, the Captain can, by simply moving an electric switch, instantly close the doors throughout, practically making the vessel unsinkable.

The last place it was described as “unsinkable” is an issue of the trade magazine, The Shipbuilder, in 1911. This article copied the promotional text above almost word-for-word, changing the end to “make the vessel practically unsinkable”.

The thing is, none of these texts were widely read. The pamphlets printed by the White Star Line were only two out of many; the first one only has one copy existing now, so it was probably in very limited circulation, too.

The Shipbuilder was expensive, and only of interest to engineers rather than the general public. And all three hedge this claim of unsinkability, using it in slight hyperbole and as a statement of intent rather than a serious claim that Titanic and Olympic could never sink.

Where the “unsinkable” claim entered the mythos is in the days after the sinking. What seems most likely to have happened is that newspaper offices had kept pieces of promotional material filed for use in researching future stories, and a few journalists pulled out clippings that included one or both of these pamphlets.

Philip Gibbs’s “The Deathless Story of the Titanic” was published soon after the sinking, and attributes the idea of the watertight doors and compartments “practically making the vessel unsinkable” (note the similarity in the phrasing) to an official description, as did the Daily Graphic‘s special memorial issue, published five days after the event.

Another cause is that the VP of the White Star Line, Philip Franklin, stated the morning after the sinking – when the details were still not fully known and rumors were flying about, some even claiming that the ship had been towed to Halifax – “We place absolute confidence in the Titanic.

We believe that the boat is unsinkable.” Where the earlier material might have been stuffed in the back of a drawer or a filing cabinet, this was said to the public, and very quickly it was multiplied into a widespread belief by the Line’s leaders, the passengers, the engineers, and the world that the ship could not possibly sink because of its state-of-the-art technology.

A narrative of overweening pride that was smashed by the deaths of more than a thousand innocents appeared almost overnight, helping to make meaning out of the enormous tragedy and make it feel deserved.