Slitherine

In Page 45 the rules state that when a battle group turns 180 degrees the bases comprising the old front rak become the new front rank and so forth.

What happens with the mixed battle groups. Let's say 2 ranks of spearmen men supported by 1 rank of skirmisher archers or the (HF spearmen - MF bowmen) types? Does that mean that after the turn the last rank of archers is found in the front? Should they reform somehow for the rest of the game?

The "old front becomes new front" rule is there specifically to allow mixed BGs to turn. The front rank of spearmen (to use your example) remains the front rank, no matter how many times the BG may turn.

Marc