The book "Dead Wake: The Last Crossing of the Lusitania" by Erik Larson discusses the evolution of submarines as military weapons. By the time of the Lusitania's fateful journey, submarines had advanced significantly and were capable of operating more safely for their crews. This advancement reflects the growing sophistication of naval warfare during World War I.

The statement highlights how submarines, which were once perilous and often led to crew fatalities, had developed into more reliable systems by that era. This change illustrates the broader technological innovations in warfare that shaped naval engagements and ultimately influenced the tragic story of the Lusitania's sinking.