The three original modules were written by Gary Gygax and were the first modules printed by TSR in 1978. Gary Gygax wrote them to take a break from writing rules in between writing the original Monster Manual and Player’s Handbook.

G1 Steading of the Hill Giant Chief was published by TSR in 1978 and written by Gary Gygax.

G2 Glacial Rift of the Frost Giant Jarl is the second in the G series of modules. It was published by TSR in 1978 and written by Gary Gygax.

G3 Hall of the Fire Giant King is the third in the G series of modules. It was published by TSR in 1978 and written by Gary Gygax. Hall of the Fire Giant King marked the first time that drow made a statistical appearance in a D&D accessory, although the 1977 edition of the Monster Manual mentioned them by name. If the DM wishes, there is a tunnel that leads deep into the earth; to the home of the drow. This allows the adventure to be continued in D1 Descent into the Depths of the Earth.

See also: http://www.canonfire.com/wiki/index.php?title=Against_the_Giants