The country on both sides of the canal is flat, and difficult for observation purposes. The high level of the water necessitates drainage of the meadows, which for this purpose are intersected by deep dykes which have muddy bottoms. The banks of the dykes are bordered with willows, and thick-set hedges form the boundaries of the cultivated areas. Generally speaking, the villages do not consist of groups of houses: the farms are dispersed either singly, or in rows forming a single street. The country is densely populated and is consequently well provided with roads. But these are only good where they have been made on embankments and are paved. The frequent rains, which begin towards the end of October, rapidly turn the other roads into mere mud tracks and in many cases make them quite useless for long columns of traffic. The digging of trenches was greatly complicated by rain and surface-water. The loam soil was on the whole easy to work in; but it was only on the high ground that trenches could be dug deep enough to give sufficient cover against the enemy's artillery fire; on the flat, low-lying ground they could not in many cases be made more than two feet deep. A few miles south of the coast the country assumes quite another character: there are no more hedges and canals: instead gently rolling sand-hills separate the land from the sea, and this deposited sand is not fertile like the plains south of them. A belt of dunes prevents the sea encroaching on the land. The greatest trouble of the attacker in all parts of Flanders is the difficulty of observation. The enemy, fighting in his own country,[20] had every advantage, while our artillery observation posts were only found with the utmost trouble. Our fire had to be directed from the front line, and it frequently happened that our brave artillerymen had to bring up their guns into the front infantry lines in order to use them effectively. Although the enemy was able to range extremely accurately on our guns which were thus quickly disclosed, nothing could prevent the German gunners from following the attacking infantry. Observation from aeroplanes was made very difficult by the many hedges and villages, so that it took a long time to discover the enemy's dispositions and give our artillery good targets. Finally, the flat nature of the country and the consequent limitations of view were all to the advantage of the defenders, who were everywhere able to surprise the attackers. Our troops were always finding fresh defensive lines in front of them without knowing whether they were occupied or not. The British, many of whom had fought in a colonial war against the most cunning of enemies in equally difficult country, allowed the attacker to come to close quarters and then opened a devastating fire at point-blank range from rifles and machine-guns concealed in houses and trees.