The sound of Russian artillery grew louder as we drove to a Ukrainian frontline position in Luhansk. The rumble of shelling sprinkled with the periodic burst of small arms fire. We were within 500 metres of the Russian positions.
This may be a conflict in the 21st century but, sometimes, with its labyrinth of trenches, it feels more like something from the First World War.
Russia's military offensive in eastern Ukraine is already intensifying. You can see it in the long queues of traffic driving west towards relative security; you can feel it in the deserted streets as you drive through the towns and cities of the Donbas; and you can hear it with the increasing noise of Russian artillery.
Russia is redeploying more of its forces from northern to eastern Ukraine. The objective is to step up the fight in the Luhansk and Donetsk - parts of which were already controlled by Russian backed separatists. Russia will make the most of its shorter supply lines - something which proved a problem in its failed offensive on the capital Kiev.
Russia and its proxies now control around 90% of Luhansk and more than half of Donetsk - the old industrial heartlands of Ukraine. There is smoke increasing throughout a landscape already scarred by mining and factories.
Ukrainian forces have been battling a war here for the past 8 years. Their systems include some of the nation's most battle hardened troops. Western officials state Ukrainian forces stationed in the Donbas are the best trained and equipped units.
As the Russian offending presses from the north, east and south there is a real risk they might soon be encircled and cut off.
Ukraine has already lost ground to Russia. However they are digging in for the battle. As we took a trip east towards the frontline we saw new defensive positions and trenches being dug.
Anatoly, a 52-year-old soldier, peered through a periscope from his trench to see the Russian positions. He told me "I see the Russians, they look like me".
But he was ready to hold the line. He said "if they attempt to take our position, I will kill them. If I don't eliminate them, they will eliminate me. It's the guidelines of war."
The majority of the men we spoke with believed that their well-prepared trenches and defences will provide the upper hand against the invaders.
Andrej, a 27-year-old soldier, was kept company in his dismal dug out by his pet dog Lucifer. He informed me "we have great weapons and excellent fortifications and if Russia attacks us here they will lose".
The troops say they've been provided with western weapons such as javelin anti-tank missiles. They were grateful, however were hoping for more.
Andrej said that President Putin is a "psycho" but he added that his dead Russian soldiers would be great fertiliser for the soil.The troops looked weary from the battling, but all stated spirits was high.
Roman, a deputy commander, had spent 4 years studying psychology at Lviv University. Along with battling he had the ability to provide his guys mental health support.
But he said "normally people don't need my assistance. They have an excellent inspiration for fighting for their family, pals and home, unlike the Russians", who he dismissively described as "zombies".
The Ukrainian soldiers are all aware that Russia is redeploying more forces to the east. They know that worse is to come.
But Roman believes that Ukraine's forces are more tactically astute. He said that Russia's military teaching had actually not progressed since World War Two, relying on weapons.That Russian artillery though is already requiring 10s of thousands of people to leave their homes.