Question: Operation Wigwam was conducted between two series of nuclear test explosions, one of which was aimed to establish military tactics for ground forces on a nuclear battlefield and was preceded by which operation?

Context paragraphs:
Operation Whetstone: The United States's Whetstone nuclear test series was a group of 46 nuclear tests conducted in 1964-1965.  These tests followed the "Operation Niblick" series and preceded the "Operation Flintlock (nuclear test)" series.

Operation Greenhouse: Operation Greenhouse was the fifth American nuclear test series, the second conducted in 1951 and the first to test principles that would lead to developing thermonuclear weapons ("hydrogen bombs").  Conducted at the new Pacific Proving Ground, specifically on islands of the Enewetak Atoll, all of the devices were mounted in large steel towers, to simulate air bursts.  This series of nuclear weapons tests was preceded by Operation Ranger and succeeded by Operation Buster-Jangle.

Operation Dominic: Operation Dominic was a series of 31 nuclear test explosions with a 38.1 Mt total yield conducted in 1962 by the United States in the Pacific.  This test series was scheduled quickly, in order to respond in kind to the Soviet resumption of testing after the tacit 1958–1961 test moratorium.  Most of these shots were conducted with free-fall bombs dropped from B-52 bomber aircraft.  Twenty of these shots were to test new weapons designs; six to test weapons effects; and several shots to confirm the reliability of existing weapons.  The Thor missile was also used to lift warheads into near-space to conduct high-altitude nuclear explosion tests; these shots were collectively called Operation Fishbowl.

Project 56 (nuclear test): Operation Project 56 was a series of 4 nuclear tests conducted by the United States in 1955-1956 at the Nevada Test Site.  These tests followed the "Operation Wigwam" series and preceded the "Operation Redwing" series.

Operation Wigwam: Operation Wigwam involved a single test of the Mark 90 Betty nuclear bomb.  It was conducted between "Operation Teapot" and "Project 56" on May 14, 1955, about 500 mi southwest of San Diego, California.  6,800 personnel aboard 30 ships were involved in "Wigwam".  The purpose of "Wigwam" was to determine the vulnerability of submarines to deeply detonated nuclear weapons, and to evaluate the feasibility of using such weapons in a combat situation.  ("See" Report of Commander) The task force commander, Admiral John Sylvester, was embarked on the task force flagship USS "Mount McKinley" .

2009 North Korean nuclear test: The 2009 North Korean nuclear test was the underground detonation of a nuclear device conducted on Monday, May 25, 2009 by the Democratic People's Republic of Korea.  This was its second nuclear test, the first test, a fizzle, having taken place in October 2006.  Following the nuclear test, Pyongyang also conducted several missile tests.  A scientific paper later estimated the yield as 2.35 kilotons.

Operation Fulcrum: The United States's Fulcrum nuclear test series was a group of 21 nuclear tests conducted in 1976-1977.  These tests followed the "Operation Anvil (Nuclear test)" series and preceded the "Operation Cresset" series.

Project Rulison: Project Rulison, named after the rural community of Rulison, Colorado, was an underground 40-kiloton nuclear test project in the United States on September 10, 1969, about 8 mi SE of the town of Grand Valley, Colorado (now named Parachute, Colorado) in Garfield County.  The location of "Surface Ground Zero" is .  The depth of the test cavity was approximately 8,400 feet below the ground surface.  It was part of the Operation Mandrel weapons test series under the name Mandrel Rulison, as well as the Operation Plowshare project which explored peaceful engineering uses of nuclear explosions.  The peaceful aim of Project Rulison was to determine if natural gas could be easily liberated from underground regions.  This site remains under active monitoring by the U.S. Department of Energy Office of Legacy Management.

Operation Teapot: Operation Teapot was a series of fourteen nuclear test explosions conducted at the Nevada Test Site in the first half of 1955.  It was preceded by "Operation Castle", and followed by "Operation Wigwam".  "Wigwam" was, administratively, a part of "Teapot", but it is usually treated as a class of its own.  The aims of the operation were to establish military tactics for ground forces on a nuclear battlefield and to improve the nuclear weapons used for strategic delivery.

Pokhran-II: Pokhran-II was the series of five nuclear bomb test explosions conducted by India at the Indian Army's Pokhran Test Range in May 1998.  It was the second Indian nuclear test; the first test, code-named "Smiling Buddha", was conducted in May 1974.

Supporting paragraphs: Operation Wigwam Operation Teapot
Answer: "Operation Castle"