Hammer's Slammers is a 1979 collection of military science fiction short stories by author David Drake. It follows the career of a future mercenary tank regiment called Hammer's Slammers after their leader, Colonel Alois Hammer. This collection, and other novels and stories in the same setting, are collectively called the Hammer stories, and the setting is called the Slammers universe or the Hammerverse.

Each of the stories in the novel follows various members of the Slammers, starting with the regiment's creation by the government of the planet Friesland to put down a revolt on the Friesland colony world of Melpomene, in which Colonel Hammer is the focal character, and who transforms the unit into an independent mercenary organization. The reader is also introduced to recurring characters such as Joachim Steuben, Hammer's bodyguard and later commander of the Slammers' military police, a gay sociopath and master marksman devoted to his colonel; Sergeant (later Major) Danny Pritchard; recruit (later Sergeant-Commander) Rob Jenne; Margritte DiManzio, whose husband is killed by mercenaries from a different regiment and signs on with the Slammers; and Sergeant "Ripper Jack" Scratchard, who shows how the Slammers infantry ties in with the regiment's combat cars and hovertanks. The book concludes with the story "Standing Down," in which Friesland revolutionaries hire the Slammers to overthrow the government of Friesland. Colonel Hammer takes over the revolution and the planet, becomes President of Friesland, and Hammer's unit becomes the 1st Regiment of the Friesland Defense Force.

Drake based the Slammers on his service with the 11th Armored Cavalry Regiment in Vietnam and Cambodia during the Vietnam War. The plots of his works are often inspired by historical or mythological sources. For example, he retells the story of Jason and the Argonauts in The Voyage, and part of the Odyssey in Cross the Stars. Other stories borrow from pulp-era fiction (The Sharp End is based on Dashiell Hammett's Red Harvest).

The novel is split into a series of short stories which follow various characters and their interactions with the Hammer's Slammers regiment. After each short story is an interlude chapter. These chapters form short essays that Drake uses to expand the world of the Hammerverse.

The first story follows Colonel Hammer himself, as well as introducing Joachim Steuben, his right-hand man and bodyguard. It opens with a conversation between Secretary Tromp, a powerful politician from the wealthy planet Friesland, and a Friesland Guards armored regiment officer, in Tromp's office at the spaceport hotel on the Friesland colony world of Melpomene. The officer has just returned from traveling with Hammer and Steuben in a convoy of armored vehicles from one of Hammer's firebases to the spaceport. Hammer had used the convoy as bait to trick the remaining Melpomene rebels into attempting an ambush on the convoy, by leaking false information that Secretary Tromp was traveling in it.

In the meantime, Hammer is in the hotel lounge, where he confronts a former fellow officer, the commander of the Guards, who is incensed that Hammer had left the elite unit to command "foreign scum." He is then summoned to Tromp's office, but he orders Steuben and another of his men to wait in their hotel suite. During a heated discussion between Hammer and Tromp, it is revealed to the reader that Hammer's Regiment (the "Slammers") was originally Tromp's idea. After several Friesland units were unable to suppress Melpomene resistance to Friesland's attempt to control the production and export of "bluebright" (a valuable pharmaceutical plant and the main product of the planet), Hammer was directed to raise a mercenary regiment and recruit non-Friesland individuals with military experience. This unit was then funded and equipped by Friesland to crush the Melpomene rebels, which they have done successfully by various means, including chemical warfare and forcing Melpomene hostages to ride on vehicles in Slammers' convoys to prevent ambushes.

It is also revealed that as one of the conditions for recruiting the regiment, the government promised that all Slammers personnel would be granted full Friesland citizenship after completing their service on Melpomene and the regiment was demobilized. However, Tromp reneges on the deal. He orders Hammer to bring the entire mercenary regiment to the spaceport where it will be disbanded under the supervision of the Guards, who have been brought to Melpomene by Tromp for that purpose.

Hammer, unwilling to have his men disarmed (and most likely executed afterwards), attempts to change Tromp's mind by suggesting that Friesland hire out the Slammers to other planets. Tromp is unmoved by this argument, stating that this would destabilize the current interstellar political system; and that Hammer should remember his loyalty to Friesland, which is more important that any promises he made to his men. Angered, Hammer leaves Tromp's office for his hotel suite. Having anticipated Tromp's betrayal, he sends a prearranged signal to his Slammers.