Complex sentence: For some time, these Confederate troops fought resolutely and brought the Union assault to a standstill, but they ran out of artillery ammunition and had to withdraw to Labadieville, opening up this portion of the Lafourche to the Union.
Split into simpler sentences: For some time, these Confederate troops fought resolutely and brought the Union assault to a standstill. The Rebels, however, ran out of artillery ammunition and had to withdraw to Labadieville, opening up this portion of the Lafourche to the Union.