(So this is how it went... in initiative order. )

Rickel's throwing knife hits the captain in the thigh. The throw was very accurate, it didn't hit any major arteries but caused enough pain for the captain's knees to buckle. He falls on his back wailing in pain.

Seira's arrow drops Heimler, who's running after Seamus.

Wiping Seamus's wine off his face, Ecker manages to load his crossbow. He looks around and realizes Heimler is dead or dying and the captain is badly injured.

"Scheisse! I surrender! Don't kill me!"

While lying on his back, the captain draws his sword and rises to a kneeling position, his face distorted in anguish.

"Pigs! Cowards! Resistance scum! Fight like men!"

It's Lydia's and Seamus's turn next, and you rolled well enough to kill Ecker. Killing a soldier who's already surrendered may affect the Resistance's reputation among the common people. (Some will consider the act heroic, while others will frown upon unnecessary killing.)