The U.S. framed the war as part of its policy of containment of Communism in south Asia, but American forces were frustrated by an inability to engage the enemy in decisive battles, corruption and incompetence in the Army of the Republic of Vietnam, and ever increasing protests at home. The Tet Offensive in 1968, although a major military defeat for the NLF with half their forces eliminated, marked the psychological turning point in the war. With President Richard M. Nixon opposed to containment and more interested in achieving détente with both the Soviet Union and China, American policy shifted to "Vietnamization," – providing very large supplies of arms and letting the Vietnamese fight it out themselves. After more than 57,000 dead and many more wounded, American forces withdrew in 1973 with no clear victory, and in 1975 South Vietnam was finally conquered by communist North Vietnam and unified.
When did this offensive take place? 
1968

Publius Vergilius Maro (Classical Latin: [ˈpuː.blɪ.ʊs wɛrˈɡɪ.lɪ.ʊs ˈma.roː]; October 15, 70 BC – September 21, 19 BC), usually called Virgil or Vergil /ˈvɜːrdʒᵻl/ in English, was an ancient Roman poet of the Augustan period. He is known for three major works of Latin literature, the Eclogues (or Bucolics), the Georgics, and the epic Aeneid. A number of minor poems, collected in the Appendix Vergiliana, are sometimes attributed to him.
How many major works of literature is Virgil known for?
three

Despite the fact that humans have occupied the territory of Portugal for thousands of years, something still remains of the original vegetation. In Gerês both deciduous and coniferous forests can be found, an extremely rare worldwide mature mediterranean forest remain in some parts of the Arrábida mountain and a subtropical laurissilva forest, dating back to the Tertiary period, covers its largest continuous area in the world in the Madeira main island. Due to the human population decrease and rural exodus, Pyrenean oak and other local native trees are colonizing many abandoned areas. Boar, Iberian red deer, roe deer, Iberian wild goat, for example, are reported to be expanding greatly, during the last decades. Boars were found recently roaming at night inside large urban areas, like in Setubal. Protected areas of Portugal include one national park (Portuguese: Parque Nacional), 12 natural parks (Portuguese: Parque Natural), nine natural reserves (Portuguese: Reserva Natural), five natural monuments (Portuguese: Monumento Natural), and seven protected landscapes (Portuguese: Paisagem Protegida), which include the Parque Nacional da Peneda-Gerês, the Parque Natural da Serra da Estrela and the Paul d'Arzila.
What two types of forests can be found in Geres?
deciduous and coniferous