"The Boys Are Back in Town" (1975–1977)
In early 1975, Thin Lizzy toured the United States for the first time, in support of Bob Seger and Bachman–Turner Overdrive. When BTO toured Europe later in the year to support their hit single "You Ain't Seen Nothing Yet", Thin Lizzy again accompanied them on what was a very high-profile tour.They then recorded the Fighting album, which became the first Thin Lizzy album to chart in the UK, reaching no. 60, although the singles still did not chart. Opening with Seger's "Rosalie", the album showed the first real evidence of the twin guitar sound that would lead the band towards their greatest successes, particularly with the dual harmonies of "Wild One" and both guitarists' soloing on "Suicide".
After a successful multi-band tour in support of Status Quo, the band recorded the album Jailbreak, which proved to be their breakthrough record. Released on 26 March 1976, it featured the worldwide hit "The Boys Are Back in Town" which reached no. 8 in the UK, and no. 12 in the US, their first charting record in that country. The twin guitar sound had been fully developed by this time and was in evidence throughout the album, particularly on the hit single, and other tracks such as "Emerald" and "Warriors". The album also charted well on both sides of the Atlantic, and the follow-up single, "Jailbreak", also performed well. Thin Lizzy toured the US in support of various bands such as Aerosmith, Rush and REO Speedwagon, and they planned to tour there again in June 1976, this time with Rainbow. However, Lynott fell ill with hepatitis and the tour was cancelled, which set them back a few months.
While Lynott was ill, he wrote most of the following album, Johnny the Fox. The album was recorded in August 1976 and the sessions began to reveal tensions between Lynott and Robertson; for example, there was disagreement over the composition credits of the hit single "Don't Believe a Word". Lynott was still drawing on Celtic mythology and his own personal experiences for lyric ideas, which dominated Johnny the Fox and the other albums of Thin Lizzy's successful mid-1970s period. The tour to support the album was very successful and there were further high-profile TV appearances, such as the Rod Stewart BBC TV Special.