A few weeks later in 1948, finding himself threatened with arrest, Neruda went into hiding and he and his wife were smuggled from house to house hidden by supporters and admirers for the next thirteen months. While in hiding, Senator Neruda was removed from office and, in September 1948, the Communist Party was banned altogether under the Ley de Defensa Permanente de la Democracia, called by critics the Ley Maldita (Accursed Law), which eliminated over 26,000 people from the electoral registers, thus stripping them of their right to vote. Neruda later moved to Valdivia, in southern Chile. From Valdivia he moved to Fundo Huishue, a forestry estate in the vicinity of Huishue Lake. Neruda's life underground ended in March 1949 when he fled over the Lilpela Pass in the Andes Mountains to Argentina on horseback. He would dramatically recount his escape from Chile in his Nobel Prize lecture.
Once out of Chile, he spent the next three years in exile. In Buenos Aires, Neruda took advantage of the slight resemblance between him and his friend, the future Nobel Prize-winning novelist and cultural attaché to the Guatemalan embassy Miguel Ángel Asturias, to travel to Europe using Asturias' passport. Pablo Picasso arranged his entrance into Paris and Neruda made a surprise appearance there to a stunned World Congress of Peace Forces, while the Chilean government denied that the poet could have escaped the country. Neruda spent those three years traveling extensively throughout Europe as well as taking trips to India, China, Sri Lanka and the Soviet Union. His trip to Mexico in late 1949 was lengthened due to a serious bout of phlebitis. A Chilean singer named Matilde Urrutia was hired to care for him and they began an affair that would, years later, culminate in marriage. During his exile, Urrutia would travel from country to country shadowing him and they would arrange meetings whenever they could. Matilde Urrutia was the muse for Los versos del capitán, a book of poetry which Neruda later published anonymously in 1952.
from "Full Woman, Fleshly Apple, Hot Moon" Full woman, fleshly apple, hot moon, thick smell of seaweed, crushed mud and light, what obscure brilliance opens between your columns? What ancient night does a man touch with his senses? Loving is a journey with water and with stars, with smothered air and abrupt storms of flour: loving is a clash of lightning-bolts and two bodies defeated by a single drop of honey.
From "Full Woman, Fleshly Apple, Hot Moon", Selected Poems translated by Stephen Mitchell (1997) 
While in Mexico, Neruda also published his lengthy epic poem Canto General, a Whitmanesque catalog of the history, geography, and flora and fauna of South America, accompanied by Neruda's observations and experiences. Many of them dealt with his time underground in Chile, which is when he composed much of the poem. In fact, he had carried the manuscript with him during his escape on horseback. A month later, a different edition of five thousand copies was boldly published in Chile by the outlawed Communist Party based on a manuscript Neruda had left behind. In Mexico, he was granted honorary Mexican citizenship. Neruda's 1952 stay in a villa owned by Italian historian Edwin Cerio on the island of Capri was fictionalized in Antonio Skarmeta's 1985 novel Ardiente Paciencia (Ardent Patience, later known as El cartero de Neruda, or Neruda's Postman), which inspired the popular film Il Postino (1994).
Second return to Chile
By 1952, the González Videla government was on its last legs, weakened by corruption scandals. The Chilean Socialist Party was in the process of nominating Salvador Allende as its candidate for the September 1952 presidential elections and was keen to have the presence of Neruda, by now Chile's most prominent left-wing literary figure, to support the campaign. Neruda returned to Chile in August of that year and rejoined Delia del Carril, who had traveled ahead of him some months earlier, but the marriage was crumbling. Del Carril eventually learned of his affair with Matilde Urrutia and he sent her back to Chile in 1955. She convinced the Chilean officials to lift his arrest, allowing Urrutia and Neruda to go to Capri, Italy. Now united with Urrutia, Neruda would, aside from many foreign trips and a stint as Allende's ambassador to France from 1970 to 1973, spend the rest of his life in Chile.
By this time, Neruda enjoyed worldwide fame as a poet, and his books were being translated into virtually all the major languages of the world. He vigorously denounced the United States during the Cuban missile crisis and later in the decade he likewise repeatedly condemned the U.S. for its involvement in the Vietnam War. But being one of the most prestigious and outspoken left-wing intellectuals alive, he also attracted opposition from ideological opponents. The Congress for Cultural Freedom, an anti-communist organization covertly established and funded by the U.S. Central Intelligence Agency, adopted Neruda as one of its primary targets and launched a campaign to undermine his reputation, reviving the old claim that he had been an accomplice in the attack on Leon Trotsky in Mexico City in 1940. The campaign became more intense when it became known that Neruda was a candidate for the 1964 Nobel Prize, which was eventually awarded to Jean-Paul Sartre (who rejected it).
In 1966, Neruda was invited to attend an International PEN conference in New York City. Officially, he was barred from entering the U.S. because he was a communist, but the conference organizer, playwright Arthur Miller, eventually prevailed upon the Johnson Administration to grant Neruda a visa. Neruda gave readings to packed halls, and even recorded some poems for the Library of Congress. Miller later opined that Neruda's adherence to his communist ideals of the 1930s was a result of his protracted exclusion from "bourgeois society". Due to the presence of many Eastern Bloc writers, Mexican writer Carlos Fuentes later wrote that the PEN conference marked a "beginning of the end" of the Cold War.
Upon Neruda's return to Chile, he stopped in Peru, where he gave readings to enthusiastic crowds in Lima and Arequipa and was received by President Fernando Belaúnde Terry. However, this visit also prompted an unpleasant backlash; because the Peruvian government had come out against the government of Fidel Castro in Cuba, July 1966 saw more than one hundred Cuban intellectuals retaliate against the poet by signing a letter that charged Neruda with colluding with the enemy, calling him an example of the "tepid, pro-Yankee revisionism" then prevalent in Latin America. The affair was particularly painful for Neruda because of his previous outspoken support for the Cuban revolution, and he never visited the island again, even after receiving an invitation in 1968.
After the death of Che Guevara in Bolivia in 1967, Neruda wrote several articles regretting the loss of a "great hero". At the same time, he told his friend Aida Figueroa not to cry for Che, but for Luis Emilio Recabarren, the father of the Chilean communist movement, who preached a pacifist revolution over Che's violent ways.