Complex sentence: SEAL Team Six's highest moment came after a highly successful classified mission executed on May 1,2011, later known as "Operation Neptune Spear", which credited SEAL Team Six with the death of Osama bin Laden, the mastermind behind the September 11 attacks.
Split into simpler sentences: SEAL Team Six's shining moment came with the execution of "Operation Neptune Spear" on May 1,2011. The operation resulted in the SEAL team getting credit for the death of Osama bin Laden, the mastermind behind the September 11 attacks.