Hurricanes with ghostly chorus
Of the Norsemen grim and stark,
Hurling oaths at giant foemen
Hacking furious in the dark!
— From North Wind at Night, by Norman Gale, as featured in The American Magazine, 1894. 
In the year of 1978, TSR Games released a most remarkable product for its Advanced Dungeons & Dragons role-playing game: the very first Dungeon Module, coded G1, an offering entitled Steading of the Hill Giant Chief.
Earlier, TSR had published the Arnesonian dungeon-fortress scenario Temple of the Frog (as edited and presented by Tim Kask and featured in D&D Supplement II: Blackmoor, 1975) and had also offered Wee Warriors’ Dungeon Masters Kit #1, Palace of the Vampire Queen (1976) through mail order. The company had further authorized a line of licensed D&D source packs and dungeon settings which were being faithfully published month-by-month via the Judges Guild, beginning with the unforgettable maps for the City State of the Invincible Overlord (1976 and after).
These milestone pre-AD&D offerings — crude and glorious as they were — were deemed, in many ways, rather ambitious, groundbreaking, and difficult to improve upon. But G1 was something special, destined to surmount them. It was superior: a high-quality, fully-illustrated product officially produced by TSR and designed by the co-author of the original Dungeons & Dragons game, E. Gary Gygax himself. Steading was fated to become the blueprint and inspirational template for the many hundreds of adventure modules which would continue to be published by various entities over the next 37 years (and counting). By many measures, G1 and its related adventures are regarded as being among the very best D&D scenarios of all time. 
As we shall see, and as many a veteran Dungeon Master would ascertain, the true legacy of G1 is inherent in the presentation of its ideas. Arguably, no other adventure supplement — with the exception of Dungeon Module B2, The Keep on the Borderlands — taught so many people how to design a quality setting for Dungeons & Dragons play. Modules come and go, and many of them are forgotten; but despite its being bare-boned, the basic format of Steading is largely still regarded as the industry standard today.
For such a gigantic (ahem) historical landmark, Steading had modest beginnings which are still somewhat shrouded in mystery. Gary worked on the module’s manuscript during a “relative hiatus”  while the Advanced Dungeons & Dragons system was still being refined from its conceptual stages, dividing itself from Basic and original D&D. This mulling over of ideas may have begun in late 1977, and was then fully written out in early 1978. (Gary recalled the year as 1978 specifically.) 
These were intense times, when Gary was working 60 to 70 hours a week on game designs while running TSR. He could take only a week or two to write G1 and to prepare it for play testing.  In observing industry sales trends throughout 1977, Gary and his coworkers had become certain that TSR needed to move into the lucrative adventure scenario sub-market with some high quality offerings of its own. He also knew that as the co-creator of D&D, he would need to author these new scenarios himself. Despite a clear market hunger for pre-scripted adventures of any kind, Gary was nevertheless reluctant to abandon the “do-it-yourself kit” approach exemplified by his earlier Dungeon Geomorphs and Monster & Treasure Assortment accessory lines.
Sadly, the sales of those toolkit products had been disappointing. The D&D accessory market was moving away from Gary’s ideal of toolkit-assisted personal craftsmanship, and ever closer to mass market convenience. Most Dungeon Masters then (as now) desired unique, fully-scripted episodes for play instead of mentoring design guides, and they would pay handsomely for the privilege. If TSR would not produce such material, then customers seeking time savers would simply look elsewhere. And other companies would be only too happy to provide complete scenarios to neophyte Dungeon Masters for cash!
For Gary, the clock was ticking. The product hunger, fan requests, and onrushing competition collectively forced his hand. As he once recalled, “TSR was getting a lot of requests for adventure modules, so I did all of the initial modules [the G and D trilogies] strictly to fill the void in the company’s product line.”  It is no coincidence that in later years, Gary would offer this sage advice to would-be game designers everywhere: “Save your ‘masterworks,’” he urged. “Instead, do the designing or writing that the audience wants.” 
As Gary and crew prepared to publish G1, the marketing aspect of this emerging product line was carefully considered within TSR. The company needed to provide its own unique elaboration upon the already existing trend toward pre-scripted adventure packs, so that TSR could establish a true flagship brand for the industry to follow. TSR was well accustomed to leading, but in this case they were already more than a year behind the times. And still more competitors were circling and moving in. How could TSR use efficacious branding to differentiate their own adventures from others’ more amateur offerings?
This need for a marketing catchword presented a bit of a problem, as Editor Tim Kask would recall,  because gamers already strongly associated the obvious term “scenario” with wargames and miniatures. But the relatively unused technical terms “module” and “modular” were in sub-cultural fashion, particularly in regards to NASA space missions, textbooks, architecture, and cognitive studies. These could be effective buzzwords. No one can quite remember whether Gary devised the term, or Tim, or Brian Blume, but the name felt right for the product at the time. The decided-upon terminology for TSR D&D adventure booklets, then, became “Dungeon Module.” This term implied not only technical specificity, but also a series of related offerings.
By definition, a “module” is a standalone preconfigured component which can be used interchangeably within a larger design. TSR was therefore underlining the fact that the dungeon modules were optional building and expansion tools, and each Dungeon Master could thus collect them all or pick and choose according to his or her need. Gary and crew planned to design the modules so that they could be used either as sequels to one another (modules G1, G2, G3, etc.), or as standalone adventures.
The early advertisement for G1 gives us further insight into the thinking behind TSR’s marketing at the time: “By using the [dungeon modules],” we read, “a Dungeon Master can moderate a pre-developed game situation with a minimum of preparation — and players can use new or existing characters for adventuring. The applications and possibilities are many — incorporation of the modules and their locales into existing D&D campaigns, or as one-time adventures simply for a change in pace.” 
The idea was solid, and TSR’s testers, artists and editor were ready to meet the project’s demands. All that Gary needed to do was to write an unforgettable adventure which everyone would want to play, setting the market path for pre-scripted modules for decades to come. Simple!
Actually, it was not simple at all.
Facing this conundrum, Gary decided to follow his instincts. He loved the pulp Swords & Sorcery genre, and some of his favorite stories involved the mytho-comedic misadventures of Harold Shea. Why not draw inspiration from the very first tale of Shea, which had playfully tweaked the poem Thrymskvitha (The Lay of Thrym) and the various sagas of Norse mythology?
Knowing he had the workings of a good idea, Gary drew his primary inspiration from The Roaring Trumpet (1940), the first Incomplete Enchanter novella written by Lyon Sprague de Camp and Fletcher Pratt.  The tale of The Roaring Trumpet is a deceptively simple one: a 20th-century intellectual bumbler becomes an accidental explorer of alternate dimensions, and to his dismay is promptly plopped down into a pre-Ragnarok clash between the giants and the gods. Amusingly, he is then forced to survive by wit alone. But he learns from his endless cultural blunders with speed and life-saving grace!
In following the example of de Camp and Pratt, Gary intended only to outline a hill giants’ fortress and to leave it at that. Steading in its earliest conception was going to be a standalone scenario. But once he started writing and the adventure’s Greyhawkian surroundings began to unfold, he found it hard to stop. There was significant potential in this modular format for a complete series of interrelated adventures, not only in marketing but in Gary’s campaign development as well. As he once explained, “I began with only the hill giants’ fort, but as that developed, the concept of a larger adventure came, so that by the time I had finished G1, the springboards for G2 and G3 were well in mind, and the whole of the underworld to follow as well.” 
FOOTNOTES TO PART I
 The term “giant foemen” is used to advertise the G-Series Dungeon Modules in the TSR Gateway to Adventure catalog, c. 1979. (Refer to my 2004 Acaeum thread, “A closer look at the 1979-1980 TSR catalog,” for further details.) Whether this was a direct deliberate allusion to the obscure older poem by Norman Gale, however, is unknown.
 The “authoritative” selection of the best D&D dungeon modules could be regarded as the 1999 Wizards of the Coast “Silver Anniversary Collector’s Edition” collection, which included reprints of the fan favorites B2, G1, G2, G3, I6, and S2. Also, super module GDQ1-7 (a series compilation including G1, G2, G3, D1, D2, D3, and Q1) was rated as the #1 pick in Dungeon magazine’s November 2004 “30 Greatest D&D Adventures of All Time.”
 The Dragon, issue #32 (February 1979), pg. 12.
 Refer to the Dragonsfoot.org thread “Lake Geneva Campaign,” and Gary’s reply made on March 3rd, 2003. See also his comments made at ENWorld.org on March 23rd, 2004, and his article “50 Years of D&D Gaming” in the Dragon Annual #4, pg. 11.
 See the Dragonsfoot.org thread “Q&A with Gary Gygax,” and Gary’s reply from February 21st, 2005.
 ENWorld.org, Q&A with Gary Gygax, as posted on April 14th, 2007.
 From “Maximize the Fun: An Interview with E. Gary Gygax,” by Anne F. Jaffe. Published in Game News, April 1985.
 Dragonsfoot.org, Q&A with Tim Kask. Posted December 8th, 2012.
 The Dragon, issue #19 (October 1978), pg. 5.
 Refer to Gary’s statement in The Dragon, issue #31 (November 1979), pg. 29.
 ENWorld.org, Q&A with Gary Gygax. Posted November 11th, 2003.