Question: What military event occurred earlier, the Battle of Belleau Wood or Tet Offensive?

Context paragraphs:
Battle of Belleau Wood: The Battle of Belleau Wood (1–26 June 1918) occurred during the German Spring Offensive in World War I, near the Marne River in France.  The battle was fought between the U.S. 2nd (under the command of Major General Omar Bundy) and 3rd Divisions along with French and British forces against an assortment of German units including elements from the 237th, 10th, 197th, 87th, and 28th Divisions.  The battle has become a key component of the lore of the United States Marine Corps.

May Offensive: During the early morning hours of 1 May, communist units initiated PHASE II of the Tet Offensive of 1968 (also known as the May Offensive, "Little Tet", and "Mini-Tet") by striking 119 targets throughout South Vietnam, including Saigon.  This time, however, allied intelligence was better prepared, removing the element of surprise.  Most of the communist forces were intercepted by allied screening elements before they reached their targets.  13 NLF battalions, however, managed to slip through the cordon and once again plunged Saigon into chaos.  Severe fighting occurred at Phú Lâm (where it took two days to root out the 267th NLF Local Force Battalion), around the Y-Bridge in Saigon, and at Tan Son Nhut Air Base.  By 12 May the offensive was over as NLF forces withdrew from the area leaving behind over 3,000 dead and 7,500 wounded.

Tet Offensive: The Tet Offensive (Vietnamese: "Sự kiện Tết Mậu Thân 1968" , or "Tổng tiến công và nổi dậy Tết Mậu Thân") was one of the largest military campaigns of the Vietnam War, launched on January 30, 1968, by forces of the Viet Cong and North Vietnamese People's Army of Vietnam against the forces of the South Vietnamese Army of the Republic of Vietnam, the United States Armed Forces, and their allies.  It was a campaign of surprise attacks against military and civilian command and control centers throughout South Vietnam.  The name of the offensive comes from the Tết holiday, the Vietnamese New Year, when the first major attacks took place.

Massacre at Huế: The Huế Massacre (Vietnamese: "Thảm sát tại Huế Tết Mậu Thân" , or "Thảm sát Tết Mậu Thân ở Huế, "lit.  translation: "Tet Offensive Massacre in Huế") is the name given to the summary executions and mass killings perpetrated by the Viet Cong (VC) and People's Army of Vietnam (PAVN) during their capture, occupation and later withdrawal from the city of Huế during the Tet Offensive, considered one of the longest and bloodiest battles of the Vietnam War.

USS Belleau Wood (CVL-24): USS "Belleau Wood was a United States Navy "Independence"-class light aircraft carrier active during World War II in the Pacific Theater, from 1943 to 1945.  The ship also served in the First Indochina War under French Navy temporary service as Bois Belleau".

USS Belleau Wood (LHA-3): USS "Belleau Wood" (LHA-3), nicknamed "Devil Dog", was the second ship named after the Battle of Belleau Wood in World War I.  Her keel was laid down on 5 March 1973 at Pascagoula, Mississippi, by Ingalls Shipbuilding.  She was launched on 11 April 1977, and commissioned on 23 September 1978, with Captain T.C. Steele in command.

Aisne-Marne American Cemetery and Memorial: The Aisne-Marne American Cemetery and Memorial is a 42 acre World War I cemetery in Belleau, Northern France.  It is at the foot of the hill where the Battle of Belleau Wood was fought, with many American fatalities.  The cemetery also contains burials from the Battle of Château-Thierry, later that summer.

Battle of Kham Duc: The Battle of Kham Duc was a major battle of the Vietnam War (also known, in Vietnam, as the "American War").  The event occurred in Khâm Đức, now district capital of Phước Sơn District, then in Quảng Tín Province (now part of Quảng Nam Province, South Vietnam), on 10–12 May 1968.  During the Tet Offensive of 1968, the Vietnam People's Army (PAVN) 2nd Division tried to capture Đà Nẵng but their attacks were quickly blunted by elements of the U.S. 1st Marine Division, the Americal Division, and the Korean Brigade that were guarding the city.  North Vietnamese General Chu Huy Mân decided to disengage from the fight in the outskirts of the city, and pull the 2nd Division into the mountains where they could rest, rebuild, and prepare for the next major operation.  Khâm Đức, a small district in the north of Quảng Tín, was chosen as the next target for the PAVN 2nd Division.  Following the defeat of the North Vietnamese in Đà Nẵng, U.S. military intelligence agencies in I Corps Tactical Zone were confused by the movements of the North Vietnamese 2nd Division, because they could not track down the mysterious enemy unit.

USS Belleau Wood: Two ships of the United States Navy have been named Belleau Wood, after the Battle of Belleau Wood near Château-Thierry in France.

American Expeditionary Forces: The American Expeditionary Forces (AEF) was the expeditionary force of the United States Army during World War I.  It was established on July 5, 1917, in France under the command of General John J. Pershing.  During the United States campaigns in World War I it fought alongside the French Army, British Army, and Canadian Army on the Western Front, against the German Empire.  A minority of the AEF troops also fought alongside the Italian Army in that same year, against the Austro-Hungarian Army.  The AEF helped the French Army on the Western Front during the Aisne Offensive (at the Battle of Château-Thierry (1918) and Battle of Belleau Wood) in the summer of 1918, and the AEF fought its major actions in the Battle of Saint-Mihiel and the Meuse-Argonne Offensive in the latter part of 1918.

Supporting paragraphs: Battle of Belleau Wood Tet Offensive
Answer: The Battle of Belleau Wood