During the winter season of 1958-59, Clemente didn't play winter baseball in Puerto Rico; instead, he served in the United States Marine Corps Reserves. He spent six months in his military commitment at Parris Island, South Carolina and Camp LeJeune in North Carolina. In Camp Lejeune, he served as an infantryman. The rigorous training program helped Clemente physically. He added strength by gaining ten pounds and said his back troubles had disappeared.
He remained in the reserves until September 1964. Early in the 1960 season, Clemente led the league, batting an average of .353 and scoring Runs Batted In (RBIs) in twenty-five out of twenty-seven games. Roberto's batting average stayed above the .300 mark throughout the course of the campaign. In August, he was inactive for five games as a result of an injury on his chin; he received this injury when his head impacted a concrete wall while he was trying to catch a hard line hit that reached the park's outer wall. Following this accident, he was transported to a local hospital, where the doctors stitched his chin; this prohibited him from playing until the injury was healed. The Pirates compiled a 95-59 record during the regular season, winning the National League pennant, and defeated the New York Yankees in a seven-game World Series. Clemente batted .310 in the series, hitting safely at least once in every game. His .314 batting average, 16 home runs, and defense during the course of the season earned him his first participation in the All-Star game, where he served as a reserve player.
During the 1961 spring training, Clemente tried to modify his batting technique by using a heavier bat in order to slow the speed of his swing, following advice from Pirates' batting coach George Sisler. During the 1961 season, Clemente was selected as the starting right fielder for the National League in the All-Star game. In this game, he batted a triple on his first at-bat and scored the team's first run. With the American League ahead 4-3 in the tenth inning, Clemente hit a double that gave the National League a decisive 5-4 win.
Following the season, he traveled to Puerto Rico along with Orlando Cepeda, who was a native of Ponce. When both players arrived, they were received by 18,000 people, who were celebrating that this was the first season in which both leagues in Major League Baseball were led in batting average by Puerto Rican players. On November 14, 1964, Clemente married Vera Zabala. The ceremony took place in the church of San Fernando in Carolina and was attended by thousands of fanatics. During this time, he was also involved in managing the Senadores de San Juan in the LBPPR, as well as playing with the team during the Major League offseason. During the course of the winter league, Clemente was injured and only participated as a pinch hitter in the league's All-Star game. He experienced a complication on his injury during the course of this game and underwent surgery shortly after being carried off of the playing field.
This condition limited his role with the Pirates in the first half of the 1965 season, during which he batted an average of .257. He was inactive for several games during this stage of the campaign before being fully active; when he returned to the starting lineup, he hit in thirty-three out of thirty-four games and his average improved to .340. Roberto and Vera had their first son on August 17, 1965, when Roberto Clemente, Jr. was born; he was the first of three children, along with Luis Roberto and Enrique Roberto. During the 1960s, he batted over .300 in every year except 1968, when he hit .291. He was selected to every All-Star game, and he was given a Gold Glove every season from 1961 onwards. He led the National League in batting average four times (1961, 1964, 1965, and 1967), led the National League in hits twice (1964 and 1967), and won the Most Valuable Player award in the 1966 season, when he hit .317 while setting career highs in home runs (29) and RBI (119). In 1967, he registered a career high .357 average and hit twenty-three home runs and 110 runs batted in.
Wikipedia about Roberto Clemente while payed for the Pittsburgh Pirates during 1958, 1959 and the 1960's.