Slitherine

The question is if enemy breaks (due to loss of bases), and the remaining bases flee in the Joint Actions phase,
will the friendly troops that follows up, step forward to contact fresh enemy?

For example(Enemy El,hf) (friends Mf)
(before the melee phase)
[El][El]
(2 inches)
[hf][hf]
[Mf][Mf][Mf]
[Mf][Mf][Mf]
[Mf][Mf][Mf]

after melee (1 elment hf dies and the hf bleaks)
[El][El]
(very small space)
[hf]
(1 inches)
[Mf][Mf][Mf]
[Mf][Mf][Mf]
[Mf][Mf][Mf]

The HF throws a 1, and move back 1 inch, will the Mf step forward to contact the El?

No, if the HF had gone past the El and they had hit the El, the pursuers would then step forward up to 2MU to hit other enemy that they could, since it would become a charge upon hitting the El, but since it has not become a charge there is no step forward

Further to Philqw78's point: if the MF hit the routing HF then the MF are making a pursuit, not a charge, and therefore do not step forward; if the HF get past the El (either by bursting through or otherwise), allowing the MF to hit the El the the MF are making a charge and might step forward into the HF.

Marc