Complex sentence: Besides the loss of the merchant ships, 3,144 men and goods worth £1.5 million were also lost, which helped to derail a secret British diplomatic effort to make a separate peace with Spain.
Split into simpler sentences: Besides the loss of the merchant ships, 3,144 men and goods worth £1.5 million were also lost. The action helped to derail a secret British diplomatic effort to make a separate peace with Spain.