Talk:Tutorial: How to Play/@comment-7963873-20150319103517/@comment-25983907-20150319104303

Either:

Failed detection, causing whole fleet of yours to lose accuracy and evasion, more at Combat.

You put too much main cannon, causing accuracy penalty due to overweight, more at Combat under common setup.

They are tired, causing them to lose accuracy, more at Morale/Fatigue.