Napoleon

The religion of the country had, in fact, changed from love of God to hatred of Napoleon Buonaparte; and, as if to remind the devout of this alteration, the pikes for the pikemen (all those accepted men who were not otherwise armed) were kept in the church of each parish.  (Chapter 23)

At the beginning of the 19th century, France had established itself as the strongest land power while England had established itself as the strongest naval power.  Napoleon strengthened the French navy in order to gain control of the seas.  At the same time, France was having great success in its battles with the rest of Europe.  However, things will come to a head off the coast of Spain at the battle of Trafalgar, which will be mentioned later in the novel. 

Hardy portrays the lives of the those in rural England as wholly consumed with the consciousness of a possible Napoleonic attack.  France's reputation as a great land power has the English countrymen fearful that the appearance of the French army will result in the loss of their homes and possibly lives.  Though not religious, Hardy illustrates the fear by the presence of the pikes in the churches and by his portrait of Squire Ferriman, who is in constant fear of his box of valuables ending up in the possession of his nephew in the event of an invasion.  Interestingly, the characters matter of factly expect the French army to show a type of war etiquette in sparing the lives of the elderly and women.

The above is Napoleon Crossing the Alps (1801) by Jacques-Louis David.