The Ukraine war has often been a grinding artillery battle. These are the big guns being sent in to pound Russian forces.

• Artillery has played a dominant role on the battlefield in Ukraine.
• When Russia invaded in February, its artillery outnumbered and outranged Ukraine's arsenal.

With foreign weapons pouring into Ukraine, the Ukrainian military may end up with one of the world's most eclectic collections of artillery.

Take howitzers, for example. When Russia invaded in February, Ukraine's army fielded the standard array of Cold War-era weapons found in former Soviet republics and satellites.

Its array of 122 mm, 152 mm and 203 mm cannon mirrored those used by Russia's military. But in the early months of the war, Ukrainian troops found themselves outnumbered and outranged by Moscow's immense arsenal of more numerous and modern weapons.

But many NATO countries have sent or promised to send a bewildering variety of weapons, including tank-like howitzers mounted on tracked chassis, wheeled cannon that more resemble big armored cars, and guns towed by trucks.

Despite bringing with it logistical and training challenges, this polyglot and hastily assembled array of firepower — along with multiple rockets launchers such as the US-made HIMARS – have enabled Ukrainian forces to counterattack successfully and begin driving Russian troops out of occupied territory.

With Ukraine depleting its stockpiles of Soviet artillery and ammunition, Western artillery will increasingly dominate Ukraine's arsenal.

Here are some of the imported howitzers that Ukraine is using:

M777

The M777 is a towed 155 mm howitzer fielded by the US Army and Marine Corps as well as the militaries of Australia, Canada, India, and Saudi Arabia. The US, Australia and Canada have sent more than 170 M777s, plus ammunition, to Ukraine.

The 5-ton howitzer, which is based on a British design, can fire regular rounds up to 15.5 miles and fire rocket-assisted projectiles out to 18.6 miles. With precision-guided rounds like the M982 Excalibur it can reach targets up to 25 miles away. The gun can be put in place — and towed away to a new firing position — within three minutes.

M777 manufacturer BAE Systems is considering restarting production of the weapon in light of renewed interest generated by its performance in Ukraine.

M198

First deployed in 1979, the M198 was replaced by the M777 in the US Army and Marine Corps around 2005.

The M198 is a heavier weapon — at about 8 tons, it's almost double what the M777 weighs — and reports indicate it has a firing range similar to the M777 with standard shells.

But with Ukraine desperately needing artillery to oppose Russia's immense number of guns, the Pentagon pulled old M198s out of storage.

M119/L119

Another British design, the UK's L119 towed 105 mm howitzer became the M119 in US service.

Weighing in at only about 2 tons, the weapon was designed for airborne and light infantry troops.

As a smaller-caliber and lighter weight howitzer, it has a reduced range of less than 12 miles.

PzH 2000

Germany and the Netherlands have already delivered 10 of the German-designed Panzerhaubitze 2000 armored self-propelled 155 mm howitzers to Ukraine.

Weighing in at 57 tons, the PzH 2000 can shoot standard shells out to a range of around 25 miles and special long-range shells out to 40 miles.

Caesar

France's Caesar is a 155 mm howitzer mounted on a six-wheeled truck.

Weighing in at about 20 tons, the Caesar can shoot out to 25 miles using regular shells or to 30 miles using rocket-assisted shells.

France has already delivered 18 Caesars to Ukraine and may deliver 12 more.

Zusana-2

The Zusana-2 is a Slovakian wheeled 155 mm self-propelled howitzer.

Germany, Denmark and Norway are buying 16 of the 32-ton weapons — which fire standard NATO 155 mm rounds — for delivery to Ukraine.

RCH-155

The RCH-155 is a new German 155 mm wheeled self-propelled howitzer.

The 39-ton vehicle, which uses the chassis from the Boxer armored personnel carrier, uses the same cannon as the PzH 2000.

Germany has promised 18 RCH-155s for Ukraine, though production will take at least three years.

M109

Ubiquitous in Western armies since the early 1960s, the M109 is a tank-like armored self-propelled 155 mm howitzer weighing in at 28 tons to 35 tons.

The older models could shoot out to about 14 miles, while the newer M109A7 Paladins — the US Army's heavily upgraded model — can reach 14 miles to 19 miles using regular and rocket-assisted projectiles and 25 miles using Excalibur guided shells.

Several nations have sent or pledged various M109 models to Ukraine, including Norway, Belgium, and Britain.

Michael Peck is a defense writer whose work has appeared in Forbes, Defense News, Foreign Policy magazine, and other publications. He holds a master's in political science. Follow him on Twitter and LinkedIn.