After composing a second string quartet -LRB- NUMBER@1 -RRB- , his strongest achievement in the world of chamber music , PERSON@1 dedicated the considerable period of seven years to his three-act tragic opera , Troilus and PERSON@2 -LRB- NUMBER@2 -RRB- .

After composing a second string quartet -LRB- NUMBER@1 -RRB- PERSON@1 spent most of the next seven years writing his opera , Troilus and PERSON@2 -LRB- NUMBER@2 -RRB- .
