1 It fortuned, as they devised had,

devised > conjectured, surmised

2 The gentle squire came riding that same way,

gentle > noble

3 Unweeting of their wile and treason bad,

Unweeting > Ignorant wile > deceitfulness, cunning

4 And through the ford to pass did essay;

essay > try

5 But that fierce foster, which late fled away,

late > recently