When in tactical action, Dutch ships used to hoist a special ensign called «Bloedvlag» (this standing for «Blood flag»). I have chosen not to represent it as an ensign in our flagsheet, but as an optional mast flag instead, in the belief that users would likely favour the normal 3-stripped ensign at stern.
As for this latter, the upper stripe was orange at start but it gradually turned into red between 1630 and 1660 –not any regulation behind, just a matter of trends apparently.
Sources: Anonymous manuscript from 1670, reprinted in Amsterdam 1966 as «Flags of the World 1669-1670» | Wikipedia(nl):Bloedvlag
Sizes: ensign W12 x L18 mm, mast flags W8 x L12 mm, jack W6 x L9 mm, pennant W4 x L48 mm.